Patricia Marino
email: patricia.marino@inserm.fr

Carole Siani

François Bertucci

Henri Roche

Anne-Laure Martin

Patrice Viens

Valérie Seror

Economic issues involved in integrating genomic testing into clinical care: the case of genomic testing to guide decision-making about chemotherapy for breast cancer patients

Keywords: cost-effectiveness, breast cancer, genomic testing, adjuvant chemotherapy

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

During the last few years, pharmacogenomic research has hold great promises for optimizing the clinical management of cancer patients. Although the pace of development of genomic tests is slower than it was expected to be a few years ago and only a few genomic tests have been marketed so far, issues about insurance coverage and reimbursement have been recently discussed in the context of increasing concern about healthcare costs [START_REF] Davis | The microeconomics of personalized medicine: today's challenge and tomorrow's promise[END_REF][START_REF] Phillips | Genetic testing and pharmacogenomics: issues for determining the impact to healthcare delivery and costs[END_REF].

The need for cost-effectiveness analyses has been stressed by many authors [START_REF] Houtsma | Pharmacogenetics in Oncology: A Promising Field[END_REF][START_REF] Vegter | Pharmacoeconomic evaluations of pharmacogenetic and genomic screening programmes: a systematic review on content and adherence to guidelines[END_REF] since these studies provide third-party payers (private and public health insurance systems) with evidence-based estimates of economic impact on which to base decision-making about coverage/reimbursement [START_REF] Deverka | Pharmacogenomics, evidence, and the role of payers[END_REF][START_REF] Drummond | Methods for the economic evaluation of health care programs[END_REF]. However, genomic testing of drug response raises specific questions relating to coverage/reimbursement. Since genomic testing and the drugs targeted in these tests should yield greater patients" well-being (due to increased effectiveness and/or fewer side-effects) than the sum of those resulting from separate use, questions arise as to how extra well-being should be assessed and handled in coverage/reimbursement decisionmaking processes. While some authors have pointed out the complementarity existing between genomic testing and the drugs targeted in the context of regulatory approval [START_REF] Davis | The microeconomics of personalized medicine: today's challenge and tomorrow's promise[END_REF][START_REF] Evans | Distinguishing product and practice regulation in personalized medicine[END_REF], complementarity has not yet been discussed to our knowledge in the context of coverage/reimbursement decisions.

In the field of breast cancer, several studies showed that gene-expression profiling could provide a useful tool for defining tumor subtypes and predicting patients" responses to treatment [START_REF] Van 't Veer | Gene expression profiling predicts clinical outcome of breast cancer[END_REF][START_REF] Van De Vijver | A gene-expression signature as a predictor of survival in breast cancer[END_REF][START_REF] Bertucci | Gene expression profiling and clinical outcome in breast cancer[END_REF]. Breast cancer is the most common female cancer occurring in industrialized countries, and is still the main cause of cancer-related death among European women [START_REF] Bray | Estimates of cancer incidence and mortality in Europe in 1995[END_REF]. The ability of adjuvant chemotherapy to improve the prognosis of breast cancer and prolong survival has been clearly established [START_REF]Early Breast Cancer Trialists' Cooperative Group (2005) Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials[END_REF], and anthracycline-based chemotherapy has been the standard adjuvant treatment for breast cancer patients during the last decade.

More recently, taxanes (docetaxel and paclitaxel) were introduced into the therapeutic sequence in the case of axillary lymph node-positive (N+) patients, in addition to regimens based on anthracylines. The majority of N+ patients in France are currently undergoing regimens based on both anthracyclines and taxanes [START_REF] Piccart | Adjuvant chemotherapy in 2005: standards and beyond[END_REF]. However, the limited benefit of taxanes in first line chemotherapy [START_REF] Mamounas | Paclitaxel after doxorubicin plus cyclophosphamide as adjuvant chemotherapy for node-positive breast cancer: results from NSABP B-28[END_REF][START_REF] Martin | Adjuvant docetaxel for node-positive breast cancer[END_REF][START_REF] Roche | Sequential adjuvant epirubicin-based and docetaxel chemotherapy for node-positive breast cancer patients: the FNCLCC PACS 01 Trial[END_REF][START_REF] Buzdar | Evaluation of paclitaxel in adjuvant chemotherapy for patients with operable breast cancer: preliminary data of a prospective randomized trial[END_REF][START_REF] Bria | Benefit of taxanes as adjuvant chemotherapy for early breast cancer: pooled analysis of 15,500 patients[END_REF] suggest that many patients probably do not benefit from the adjunction of taxanes [START_REF] Campone | Taxanes in adjuvant breast cancer setting: which standard in Europe?[END_REF]. In this context, genomic testing might improve the effectiveness of treatments by determining which patients are likely to benefit most from them, thus avoiding unnecessary therapy and ensuring more cost-effective care [START_REF] Davis | The microeconomics of personalized medicine: today's challenge and tomorrow's promise[END_REF][START_REF] Veenstra | Assessing the cost-effectiveness of pharmacogenomics[END_REF][START_REF] Flowers | The role of cost-effectiveness analysis in the era of pharmacogenomics[END_REF][START_REF] Guttmacher | Genomic medicine--a primer[END_REF].

To investigate these issues, a cost-effectiveness analysis was conducted in which the impact of tumour gene expression profiling was assessed in patients with early N+ breast cancer treated with adjuvant chemotherapy [START_REF] Bertucci | Gene expression profiles of poorprognosis primary breast cancer correlate with survival[END_REF][START_REF] Bertucci | Gene expression profile predicts outcome after anthracyclinebased adjuvant chemotherapy in early breast cancer[END_REF]. More specifically, the aim of the study was to assess the cost-effectiveness of genomic testing used to identify whether or not N+ breast cancer patients are likely to benefit from a regimen based on anthracyclines alone, i.e. without the adjunction of taxanes. While an ongoing prospective multicentre study (involving three French cancer centers) is focusing on the clinical benefits associated with routine use of gene expression profiling, the present study is based on the currently available retrospective data.

This study presents findings on the expected impact of gene expression profiling in terms of both health outcomes and costs of care, and discusses some issues relating to the coverage/reimbursement of genomic testing.

Material and methods

The data set

The present cost-effectiveness analysis was performed using on data from the PACS 01 randomized clinical trial [START_REF] Roche | Sequential adjuvant epirubicin-based and docetaxel chemotherapy for node-positive breast cancer patients: the FNCLCC PACS 01 Trial[END_REF] carried out by a network of French national cancer centers (FNCLCC). In this trial, anthracyline-based chemotherapy (6 cycles of FEC 100) was compared with a combined anthracycline and taxane regimen (3 FEC 100 followed by 3 cycles of docetaxel) in the adjuvant setting in 1999 N+ breast cancer patients. In addition to the clinical data, individual economic data on the patients" hospital care (surgery, chemotherapy and other drugs, laboratory investigations, length of hospital stay, etc;) were available [START_REF] Marino | Cost-effectiveness of adjuvant docetaxel for nodepositive breast cancer patients: results of the PACS 01 economic study[END_REF].

Tumour genotyping was performed (by Ipsogen, Marseilles, France, http://www.ipsogen.com/) using DNA microarrays from frozen samples collected from 246 patients enrolled in the PACS 01 clinical trial. Among these 246 patients, 128 received a chemotherapy regimen based on anthracylines alone and 118 received a combined anthracyline plus taxane regimen.

We recently described a 189-gene expression signature predictive of metastatic relapse after adjuvant anthracycline-based chemotherapy without taxane [START_REF] Bertucci | Gene expression profile predicts outcome after anthracyclinebased adjuvant chemotherapy in early breast cancer[END_REF]. This signature was identified in a learning set of 323 patients and subsequently validated in an independent set of 175 patients. Based on this signature, the 246 patients were retrospectively categorized into a good prognosis group (patients likely to benefit from a regimen based on anthracyclines alone) and a poor prognosis group (patients unlikely to benefit from a regimen without taxane). In all, 197 out of the 246 patients were identified as having a good prognosis (105 of the patients in this group received an anthracycline-based chemotherapy and 92 received an anthracycline plus taxane regimen), and 49 were identified as having a poor prognosis (anthracycline-based chemotherapy and anthracycline plus taxane chemotherapy administered to 23 and 26 patients, respectively).

Specification of strategies

In the present cost-effectiveness analysis, the current standard treatment strategy for N+ breast cancer patients [START_REF] Roche | Sequential adjuvant epirubicin-based and docetaxel chemotherapy for node-positive breast cancer patients: the FNCLCC PACS 01 Trial[END_REF] was compared with the innovative strategy involving gene expression profiling to guide decision-making about chemotherapy (Figure 1). More specifically, the following strategies were compared:

1. The AT strategy: all patients received a regimen of 3 cycles of anthracyclines followed by three cycles of docetaxel (3 FEC 100 + 3 docetaxel), which is the standard treatment for N+ patients in France [START_REF] Roche | Sequential adjuvant epirubicin-based and docetaxel chemotherapy for node-positive breast cancer patients: the FNCLCC PACS 01 Trial[END_REF].

2. The GEN strategy: all the patients" tumors were genotyped, and the chemotherapy received by patients depended on the results of the gene-expression profiling: 6 cycles of anthracycline-based chemotherapy (FEC100) in good prognosis patients, and anthracyline plus taxane chemotherapy (3 FEC 100 + 3 docetaxel) in poor prognosis patients.

Since some patients were included in both AT and GEN strategies, comparisons between strategies in terms of effectiveness and costs required specific statistical methods: these are described in the "Statistical Analysis" Section.

Effectiveness of strategies

The endpoint adopted to assess the effectiveness of these strategies was metastasis-free survival (MFS), as this was the clinical outcome used to identify the gene expression patterns correlated with patients" prognosis. MFS was calculated from the date of diagnosis up to the date of first distant metastasis. Patients who did not have any metastatic relapse were censored. Survival rates and mean survival times were calculated using the Kaplan-Meier method. The variance estimator of the survival times was calculated using bootstrap methods, since no simple expression for this parameter is available. Bootstrap tests were also conducted to determine the equality of mean survival times (for further details, see the "Statistical analysis" Section).

Treatment Costs

The costs included in the analysis were from the healthcare provider perspective, taking only medical costs into account. As with the effectiveness data, the cost data were obtained on the 246 patients included in the PACS 01 trial [START_REF] Marino | Cost-effectiveness of adjuvant docetaxel for nodepositive breast cancer patients: results of the PACS 01 economic study[END_REF]. The cost analysis was performed using the micro-costing method, which consisted in measuring resource utilization in physical quantities, combined with a monetary valuation using unit cost data [START_REF] Drummond | Methods for the economic evaluation of health care programs[END_REF]. Physical quantities involved in medical resource utilization were collected prospectively alongside the PACS 01 trial.

The following resource items were collected for calculating costs:

Hospital stays: inpatient stays (number of days) and day clinic visits (number of visits) Pharmacy: quantities of drugs administered (chemotherapy, antibiotics, Filgrastim G-CSF, anti-emetics, etc.) Laboratory: the tests and medical investigations specified in the clinical protocol (including pre-treatment tests).

Surgical procedure: mastectomy or breast conserving surgery (lumpectomy).

Monetary values expressed in euros (€) were attributed to all physical quantities consumed (based on the current rate of exchange, 1€ is worth about 1.30US$). Because of the wellknown differences existing between hospital charges and real costs [START_REF] Finkler | The distinction between cost and charges[END_REF], especially in the context of a publicly funded health care system such as the French one, hospital charges were not used to assess the costs associated with hospitalization. Instead of hospital charges, "real cost" per diem of hospitalizations and outpatient visits were used, based on the detailed data on annual expenditures that were routinely collected at a French cancer center"s analytic accounting system (Institut Paoli-Calmettes). These costs included that of the staff involved, depreciation of equipment (using a depreciation rate of 20%), consumable supplies, and food costs. A 20% overhead rate was added to these hospital costs to account for the administrative resources used [START_REF] Drummond | Methods for the economic evaluation of health care programs[END_REF]. Drug prices were the purchase prices negotiated at national level by the Federation of French Cancer Hospitals. Costs of laboratory tests, diagnostic tests and surgical acts were based on the tariffs applied by the French national health insurance system.

Since the clinical trial involved collecting economic data from randomization in the PACS 01 trial up to the end of chemotherapy, the total costs of the treatments were calculated only during this period of time. This limitation can be partly justified by the fact that the posttreatment follow-up and laboratory tests conducted after completion of the treatment were likely to be the same, regardless of which of the two treatment strategies was used.

Cost-effectiveness

In most cost-effectiveness analyses, the results of comparisons between strategies of care are generally expressed in terms of incremental cost-effectiveness ratios (ICER), which give the additional cost required to reach one additional unit of effectiveness. However, as genomic profiling was designed to avoid over-treatment (adding taxanes) without reducing the effectiveness of chemotherapy [START_REF] Bertucci | Gene expression profile predicts outcome after anthracyclinebased adjuvant chemotherapy in early breast cancer[END_REF], the cost-effectiveness analysis could be reduced to a costminimization analysis once the validity of the hypothesis that the effectiveness of both strategies was similar had been confirmed.

Statistical analysis

Since some patients were included in both the AT and GEN strategies (patients having received anthracycline-and taxane-containing regimens and retrospectively identified as having a poor prognosis based on the results of gene-expression profiling), correlations between the data make the standard statistical methods not appropriate. To deal with this problem, bootstrap methods were used which consist in resampling and simultaneously replacing variables (costs, survival times, occurrence of events, and strategy) to preserve the correlations between them. This procedure was repeated a large number of times [START_REF] Bertucci | Gene expression profiling and clinical outcome in breast cancer[END_REF]000 times in this case). Based on the variance of the survival differences and the variance of the costs differences thus obtained, bootstrap tests were carried out to determine the equality of mean survival times and the equality of average costs. Confidence intervals were calculated on the difference between the mean costs of the two strategies compared.

Sensitivity analysis

Sensitivity analyses were conducted by varying some key parameters in order to assess the robustness of the cost findings. Given the high likelihood that genomic testing would strongly affect the cost of the GEN strategy, the first key parameter tested was the cost of genomic testing (including preservation and transportation of the samples, RNA extraction, as well as the price of genomic testing, which has not yet been set). The second key parameter in the assessment of the AT and GEN strategies was the purchase price of docetaxel, since this drug will soon become available as a generic drug (patent rights expired in 2010 in the US and most European countries), and will therefore cost less than its brand name counterpart. These parameters were varied simultaneously (cost of genomic testing was taken to be in the 0€-5,000 € range, and the price of docetaxel was taken to decrease by -10% to -60% ), and the difference between the costs of the two strategies (including 95% CI) was calculated.

Results

The clinical characteristics of the 246 patients included in this analysis are presented in Table 1. All the patients were between 29 and 64 years of age and they all had histologically confirmed axillary lymph node involvement without any metastases. Among these 246 patients, 128 received an anthracycline-based chemotherapy without taxane, and 118 received combined anthracycline/taxane chemotherapy. The regimen involving anthracyline consisted of fluorouracil 500mg/m², epirubicin 100mg/m² and cyclophosphamide 500mg/m². The chemotherapy regimen involving taxane consisted of three cycles of the same FEC regimen, followed by three cycles of docetaxel 100mg/m². The patients" clinical characteristics were well balanced between treatment groups (anthracycline vs taxane, p>0.05 in all the cases). Among these 246 patients, genomic testing led to identifying 197 patients (80.1%, 95%CI: 75.1%-85.1%) as having a good prognosis, while the remaining 49 patients (19.9%, 95%CI: 14.9%-24.9%) were found to have a poor prognosis. Since the clinical PACS 01 trial was not designed to assess the impact of genomic testing on patients" health outcomes, it emerged that 53.3% of the patients with a good prognosis received a chemotherapy regimen without taxane while 47.7% received a combined anthracycline/taxane regimen. Conversely, 47.9% of the patients classified as having a poor prognosis received a taxane-free chemotherapy regimen, while 53.1% received a combined anthracycline/taxane regimen (Table 2).

Effectiveness of therapeutic strategies

The survival rates are summarized in Table 2. Effectiveness of strategies was calculated in terms of metastasis-free survival (MFS) during a median follow-up time of 60 months. The 5year MFS was 81.4% in the case of the AT strategy and 83.4% in that of the GEN strategy (p=0.34).

Patients in the good prognosis group had similar survival times regardless of the treatment undergone (5-year MFS was 87.0% and 84.9%, depending on whether or not the chemotherapy regimen included taxanes), which suggests that these patients did not benefit from the adjunction of taxanes. In the poor prognosis group, the 5-year MFS was higher among the patients who had received taxane than among those who had not (69.2% vs 60.9%), although this difference was not statistically significant because of the small numbers involved (p=0.58).

Treatments costs and cost-minimization analysis

Based on the measurement of the resources individually consumed by the 246 patients involved in the analysis, the average treatment costs associated with the AT and GEN strategies are presented in Table 3, along with the proportions of the costs attributable to the various cost categories. Note that the treatment cost values given in Table 3 include docetaxel priced as a brand name drug.

Taking only the costs incurred during the treatment period, the mean cost per patient in the case of the AT strategy was 12,688€ (95%CI: [12,329 ; 13,047]), where the purchase cost of taxanes amounted to 31.9% of the total cost. In the case of the GEN strategy, the mean cost per patient (not including the cost of gene expression profiling) was 10,184€ (95%CI: [9,825 ; 10,543]), which is 19.6% lower than with the AT strategy. With cost savings of 2,504€ per patient (95%CI: [-2,999 ; -2,010]) without any loss of effectiveness, the GEN strategy therefore turned out to be preferable to the standard docetaxel-based AT strategy (p<0.001).

Since gene expression profiling is currently performed only in clinical trials designed to prospectively assess patients" health outcomes, it is not covered by the French health insurance system and has therefore not been priced. Taking the cost of genomic testing into account yielded the results presented in Figure 2. With genomic testing costs below 2,090€ (including tumour sample preparation, transportation, and testing), the GEN strategy dominated the AT strategy as it was significantly less costly; whereas taking the costs of genomic testing to amount to more than 2,919€ made the strategy AT cost-effective. When the genomic testing costs ranged between these two values, the total cost of AT and GEN strategies was similar, and the two strategies were therefore equivalent. Since all the results presented above were based on docetaxel priced as a brand name drug, and since taxanes accounted for 31.9% and 7.3% of the mean cost of strategies AT and GEN, respectively, a sensitivity analysis was carried out on the cost of genomic testing and that of docetaxel (Figure 2). Since generic drugs usually cost about 30%-40% less than their brand name counterparts, a 30% decrease in the price of docetaxel was applied. In this case, the GEN strategy dominated the AT strategy when the cost of genomic testing was in the 0€-1,139€ range. Conversely, the AT strategy was cost-effective when the cost of genomic testing was taken to be greater than 1,891€. The two strategies were found to be equivalent when the cost of genomic testing was taken to range between 1,139€ and 1,891€.

Discussion

Gene expression profiling could help to refine medical decision-making, but some questions about its economic impact need to be addressed before it can be used in routine clinical settings [START_REF] Sims | High-throughput genomic technology in research and clinical management of breast cancer. Exploiting the potential of gene expression profiling: is it ready for the clinic?[END_REF][START_REF] Roden | Pharmacogenomics: challenges and opportunities[END_REF]. It is thus necessary to determine whether the use of genomic testing yields clinical benefits that justify the additional cost of testing all patients [START_REF] Flowers | The role of cost-effectiveness analysis in the era of pharmacogenomics[END_REF][START_REF] Swen | Translating pharmacogenomics: challenges on the road to the clinic[END_REF]. Although the cost of genomic testing is likely to be substantial, targeting treatments more selectively to those patients who are likely to benefit most might prevent therapeutic escalation and the corresponding costs.

The present assessment of the potential impact of gene expression profiling on the cost of treatment and the survival of N+ breast cancer patients shows that the therapeutic strategy involving genomic testing is potentially cost-effective, depending on the cost of genomic testing. With costs lower than 2,090€ at the current drug prices (or less than 1,139€ when the price of docetaxel was assumed to drop by 30% once it has become a generic drug), treatment decisions based on gene expression profiling were found to be equally effective but significantly less costly than the strategy involving taxanes administered to all patients.

Taking the cost of genomic testing to be in the 2,090€ to 2,919€ range (or in the 1,139€ to 1,891€ range if the price of docetaxel decreases by 30%), the two strategies were found to have similar costs and effectiveness. It is worth noting that these costs (including tumour sample preparation and transportation) turned out to be lower than the price of the currently available genomic tests for breast cancer patients ($3,460 for Oncotype DX [START_REF] Ross | Commercialized multigene predictors of clinical outcome for breast cancer[END_REF], for example). This analysis is subject to a number of limitations. First, the number of patients in our study sample was rather small, especially in the case of the poor prognosis group, in which the patients received an anthracyline plus taxane chemotherapy regimen. Another limitation is the existence of some uncertainty about the predictive value of gene expression profiling, as the clinical findings were based on retrospective data [START_REF] Bertucci | Gene expression profile predicts outcome after anthracyclinebased adjuvant chemotherapy in early breast cancer[END_REF]. However, the latter limitation is common to many studies, and no direct evidence has been provided so far that gene expression profiling improves breast cancer patients" outcomes [START_REF] Lyman | Gene expression profile assays as predictors of recurrence-free survival in early-stage breast cancer: a metaanalysis[END_REF].

A few studies have addressed the economic impact of gene expression profiling in the treatment of breast cancer patients. The results of these studies are not directly comparable with ours, however, mainly because of the differences between the therapeutic indications for gene expression profiling (N+ patients in our case, versus N-patients in previous studies). In the study by Hornberger et al., the cost-utility of using a 21-gene expression signature to reclassify patients initially defined as low-or high-risk patients according to the National Comprehensive Cancer Network (NCCN) clinical guidelines, was calculated as $31,452 per QALY gained, and the authors concluded that genomic testing has the potential to increase quality-adjusted survival and save costs [START_REF] Hornberger | Economic analysis of targeting chemotherapy using a 21-gene RT-PCR assay in lymph-node-negative, estrogenreceptor-positive, early-stage breast cancer[END_REF]. These results were recently confirmed on a larger set of patients [START_REF] Lyman | Impact of a 21-gene RT-PCR assay on treatment decisions in early-stage breast cancer: an economic analysis based on prognostic and predictive validation studies[END_REF]. The study by Oestreicher et al. led to similar conclusions and suggested that performing gene expression profiling to identify the high-risk breast cancer patients who are likely to benefit most from adjuvant chemotherapy may yield net cost savings of $2,882 per patient [START_REF] Oestreicher | Gene expression profiling and breast cancer care: what are the potential benefits and policy implications?[END_REF]. All these studies were based on retrospective data, and their authors pointed out that the evidence about the economic outcomes was not very solid, since cost-effectiveness is difficult to assess until the clinical relevance of genomic testing for treatment decision-making purposes is confirmed.

In view of the need expressed for cost-effectiveness analyses to inform decision-making about coverage/reimbursement, it is worth noting that cost-effectiveness findings do not actually solve this issue. Coverage/reimbursement decisions cannot be reduced to a matter of balancing health insurance budgets, since they are liable to affect the development of the newly developing pharmacogenomic sector: low pricing might create a negative incentive for developing new genomic tests, whereas high pricing might favour opportunities for rent seeking that would actually be financed by the health insurance subscribers.

Another issue relating to coverage/reimbursement is that genomic testing and the drug targeted are complementary [START_REF] Chen | One-Way Essential Complements[END_REF][START_REF] Gabszewicz | On Price Competition with Complementary Goods[END_REF], which means that their joint use results in greater wellbeing than the sum of those resulting from separate use. In particular, undergoing genomic testing generates very little if any well-being if the drug targeted is not available. Since higher value is usually attached to greater well-being, the question arises as to how increased wellbeing should be priced. In view of the fact that genomic testing is intended to prevent overtreatment and to reduce the magnitude and/or frequency of side-effects, well-being could be approached by assessing patients" quality of life. Although the issue of the monetary value of quality of life has been addressed by a few authors [START_REF] Hirth | Willingness to pay for a quality-adjusted life year: in search of a standard[END_REF][START_REF] Pinto-Prades | Trying to estimate a monetary value for the QALY[END_REF][START_REF] Mason | Modelling the monetary value of a QALY: a new approach based on UK data[END_REF], these studies are still in the exploratory stage.

The last point concerns the use of thresholds to classify patients depending on the results of genomic testing. In line with the premises of "personalized medicine", it seems somewhat contradictory to determine individual gene expression profiles and then express the results in terms of belonging to a group. Greater consistency could be achieved by expressing individual genomic test results in terms of the probability of responding to the drug targeted, for example. This would enable physicians and patients to make better informed decisions and inform the payers" decision-making about coverage, since the question would then arise as to how an "acceptable" probability of responding to drugs should be defined.

Conclusion

The introduction of new drugs in the adjuvant setting often yields rather low and heterogeneous benefits and generates morbidity and financial costs. The use of genomic tests targeting currently available drugs might therefore provide a useful means of preventing therapeutic escalation and the associated costs. The results of the present study suggest that genotyping breast cancer patients to guide medical decision-making about chemotherapy : restricting the administration of taxanes to those patients who are most likely to benefit from the treatment should decrease the cost of care. Further cost-effectiveness analyses based on prospectively collected data are now required to confirm these preliminary findings. Clinical trials could also provide insights on patients" quality of life and the acceptability of genomic testing to physicians and patients as a means of guiding decision-making about chemotherapy.

Tables and figures

Table 1. Clinical characteristics of patients included in the cost-effectiveness analysis. Table 2. 5-year MFS of good and poor prognosis patients, according to the treatment received. Table 3. Treatment costs associated with strategies AT and GEN.

Figure 1 .

 1 Figure 1. Decision tree: the two strategies compared

Figure 2 .

 2 Fig1. Decision tree: the two strategies compared

Table 1 . Clinical characteristics of patients included in the cost-effectiveness analysis

 1

		All patients	Patients receiving	Patients receiving
			6 FEC 100 1	3 FEC 100 + 3 Docetaxel 2
		(n=246)	(n=128)	(n=118)
	Age (years)
	mean ± sd	50 ± 8	50 ± 7.6	50 ± 8.3
	range	29-65	31-65	29-65
	Hormonal status
	premenauposal	145 (59.4%)	77 (60.6%)	68 (58.1%)
	menauposal	99 (40.6%)	50 (39.4%)	49 (41.9%)
	ER status
	negative	56 (22.8%)	33 (25.8%)	23 (19.5%)
	positive	190 (77.2%)	95 (74.2%)	95 (80.5%)
	PR status
	negative	82 (33.3%)	41 (32.0%)	41 (34.7%)
	positive	164 (66.6%)	87 (68.0%)	77 (65.3%)
	SBR grade
	SBR I	41 (16.9%)	20 (15.9%)	21 (17.9%)
	SBR II	91 (37.4%)	46 (36.5%)	46 (39.0%)
	SBR III	105 (43.2%)	58 (46.0%)	47 (39.8%)
	non gradable	6 (2.5%)	2 (1.6%)	4 (3.4%)
	Number of involved lymph nodes
	mean ± sd	3.95±4.0	3.97 ± 3.9	3.80 ± 3.9
	range	1-23	1-22	1-23
	<= 3	151 (61.6%)	80 (62.5%)	71 (61.0%)
	> 3	94 (38.4%)	48 (37.5%)	46 (39.0%)
	Genomic testing
	Good prognosis	197 (80%)	105 (82%)	92 (78%)
	Poor prognosis	49 (20%)	23 (18%)	26 (22%)

Table 2 . 5-year MFS* of good and poor prognosis patients, according to the treatment received.

 2 MFS: metastasis-free survival1 6 cycles of fluorouracil 500mg/m², epirubicin 100mg/m² and cyclophosphamide 500mg/m².2 6 cycles of fluorouracil 500mg/m², epirubicin 100mg/m² and cyclophosphamide 500mg/m² followed by 3 cycles of Docetaxel 100mg/m²,

			Receiving
	All patients n=246	6 FEC 100 1	3FEC100 + 3Docetaxel 2
		(n=128)	(n=118)
	Good prognosis (n=197)	n=105	n=92
	5-year MFS % survival	87.0%	84.9%
	95% IC	[78.6% ; 92.3%]	[75.3% ;91.0%]
	Poor prognosis (n=49)	n=23	n=26
	5-year MFS % survival (95% IC)	60.9%	69.2%
	95% IC	[38.3% ; 77.4%]	[47.8% ; 83.3%]

*

Table 3 . Treatment costs associated with strategies AT and GEN * Strategies

 3

	According to genomic profile (n=131)

6 cycles of fluorouracil 500mg/m², epirubicin 100mg/m² and cyclophosphamide 500mg/m².

3 cycles of fluorouracil 500mg/m², epirubicin 100mg/m² and cyclophosphamide 500mg/m² followed by

cycles of Docetaxel 100mg/m², ER: oestrogen receptor ; PR: progesterone receptor; SBR: Scarff Bloom Richardson

Acknowledgements

This study was supported by a grant from the "Fondation de France". The authors thank Dr.

Jessica Blanc for revising the English manuscript. The authors also thank Christian de Peretti for valuable discussions about bootstrap.


Guillaume Galy
email: guillaume.galy@chu-lyon.fr

Sana Intidhar Labidi-Galy

David Pérol

Thomas Bachelot

Isabelle Ray-Coquard

Olivier Tredan

Pierre Biron

Jean-François Latour

Jean-Yves Blay

Jean-Paul Guastalla

David Perol

Bertrand Favier

-1998 and 2003-2006

Keywords: Metastatic breast cancer, chemotherapy, survival, costs, medico-economic study

Chemotherapy for metastatic breast cancer. Comparison of clinical practice and cost of drugs in two cohorts of patients: 1994

Introduction

Despite recent advances in early detection and treatment, breast cancer remains the leading cause of death by cancer in women. At metastatic stages, there is no single standard of care for the patients, as treatment plans require an individualized approach based on multiple factors including specific tumor biology, presence of visceral metastases, history of prior therapy and response, and patient preference.

Metastatic breast cancer (MBC) remains an incurable disease, and treatments are aimed to improve patient quality of life and possibly to prolong survival without excessive toxicity. The average survival time is no longer than 2 years [START_REF] Hortobagyi | Treatment of breast cancer[END_REF].

Because of the chemosensitivity of the disease, the large majority of MBC patients are candidates for chemotherapy, either upfront or after failure of hormonal treatments. Over the last decade, new chemotherapy drugs, including capecitabine, gemcitabine and liposomal doxorubicin, have been developed and approved in this setting. In addition, targeted biologic agents, such as trastuzumab, bevacizumab and lapatinib, combined with traditional chemotherapies appear to offer new treatment opportunities. These molecules have been approved based on the results of hundreds of randomized trials comparing chemotherapy drugs, doses, combinations, sequences and durations. But it is important to note that only eight of these trials have shown improved survival in MBC patients [START_REF] Wilcken | Chemotherapy in metastatic breast cancer: A summary of all randomised trials reported 2000-2007[END_REF][START_REF] Carrick | Single agent versus combination chemotherapy for metastatic breast cancer[END_REF]. Furthermore, most published clinical trials have focused on first-line chemotherapies and few have evaluated the cost-efficacy of new drugs [START_REF] Priol | Cost-effectiveness analysis of capecitabine in combination with docetaxel in comparison to docetaxel monotherapy in advanced or metastatic breast cancer in France][END_REF]. In the context of current health policy, with a majority of governments trying to limit the escalation of health care expenditures, such analysis may contribute to the on-going debate about the dissemination of innovative cancer drugs.

In this retrospective study, we examined temporal trends in the use of chemotherapeutic agents for the treatment of MBC in the context of clinical practice and their costs. We also performed a study of the survival rates of MBC patients over time.

Materials and Methods

Patient selection

The patients included in this retrospective study were selected among MBC patients treated by chemotherapy at Léon Bérard Cancer Center (CLB), Lyon, France. The extent of metastatic involvement was determined by physical examination and routine imaging procedures including chest x-ray, liver ultrasound and bone scan before initiation of medical treatment. Information regarding date of diagnosis, patient age, Scarff-Bloom and Richardson (SBR) grade and TNM stage [START_REF] Singletary | Revision of the American Joint Committee on Cancer staging system for breast cancer[END_REF] of the initial tumor, performance status (PS), disease-free interval from initial diagnosis, number and sites of metastases, hormone receptor (HR) status, HER-2 status and medical treatments in the adjuvant and metastatic settings was obtained from original patient records. A treatment was considered delivered when at least one dose of the drug was received by the patient. The data were last updated in April 2008.

Chemotherapy drugs

The patients identified from the CLB breast cancer database were cross-referenced with the pharmacy database to collect information on the chemotherapeutic drugs used for their treatment. The pharmacy database records the date, the type and dose of all systemic agents administered in the hospital or at home and indications for their use in the treatment of a specific cancer in a given patient. For oral chemotherapy drugs purchased from local retail pharmacies, information was retrieved from original patient records and prescriptions. The line of chemotherapy (LOC) was defined as the interval from the date of the beginning of a treatment to the date of progression.

Cost analysis

The cost analysis was limited to the direct costs of chemotherapy drugs, thus excluding the costs of drug preparation and administration, hospitalization and transportation. The respective costs of chemotherapy agents were calculated from the beginning of treatment to death or end of the study. They were estimated in Euros (€, 2008) from the perspective of the French health care system. For treatments administered in the hospital, we determined the exact number of milligrams per prescription and per patient, and then we multiplied this quantity by the purchase price of each drug as nationally negotiated by the federation of French cancer centers (FNCLCC) with which the CLB is affiliated. The treatments administered at home were identified by examination of the follow-up records of the patients. We determined the number of vials per prescription and per patient, and we calculated the total cost of the treatment, assuming that every vial opened at home was used (unused drug in opened vials was discarded). For oral chemotherapy drugs purchased from local pharmacies, the number of milligrams per prescription was determined and valued using prices fixed by the French public health authorities.

Statistical analysis

The characteristics of the patients were compared using Pearson's Chi-square test (or Fisher's exact test, if necessary) and Student's t test. Overall survival (OS) was defined as the time from diagnosis of metastasis to date of death or date of last follow-up for patients alive at last contact. Survival distributions were estimated by the Kaplan-Meier method [START_REF] Kaplan | Nonparametric estimation from incomplete observations[END_REF]. To evaluate the relationship between survival and biological and/or clinical factors known to be relevant in MBC, all potential prognostic factors were included in univariate Cox proportional hazard regression models [START_REF] Dr | Regression model and lifer tables (with discussion)[END_REF].

Candidate prognostic factors with a 0.05 level of significance in univariate analysis were then selected for inclusion in the multivariate analysis. Independent prognostic variables of survival were identified by a Cox regression analysis using a backward selection procedure to adjust the time cohort effect on patient's characteristics. All statistical analyses were performed using SAS software v.9.1 (Cary). All P values for two-tailed tests were considered significant when P<0.05.

Results

Patient characteristics

In total, 301 of 957 MBC patients of treated in our institution between 1994 and 2006 fulfilled the study criteria. Group 1 included 149 patients treated with chemotherapy between 1994 and 1998, and group 2 included 152 patients treated between 2003 and 2006. The median follow-up for surviving patients was 3.87 years for the entire cohort. Patient characteristics are listed in table 1. Overall, missing data were more frequent in group 1. Patient characteristics did not statistically differ between groups, except for age; patients of group 1 were younger than those of group 2. HR and HER-2 status were more frequently known in group 2. All patients of group 1 with positive HR status received adjuvant hormone therapy, compared to only 64 patients (53.8%) in group 2 (P<0.001). Similarly, a greater proportion of patients in group 1 received hormone therapy for MBC (table 1) and this did not correlate with HR status. Thus, 27 patients (81%) with negative HR status received hormone therapy in group 1, compared to only 12 patients (21.4%) in group 2 (P<0.001).

The majority of patients from both groups received adjuvant chemotherapy, in particular anthracyclines (Table 1). Only one patient from group 1 received taxanes in the adjuvant setting, compared to 18 patients (15.1%) from group 2 (p<0.001).

Chemotherapy drugs administered for MBC

The various chemotherapeutic agents used for the treatment of MBC in the patients of the two time groups are outlined in table 2. Overall, there was no significant difference between groups in the median number of LOC (n=3). There was a trend toward a reduction in the use of anthracyclines over time. The quasi-totality of group 1 patients (93.3%) received anthracyclines, most of them in first line (77.2%), compared to only 50% of group 2 patients. The lower use of anthracyclines in the metastatic setting in group 2 was correlated with an increased use in the adjuvant setting. Taxanes, trastuzumab and capecitabine were more frequently administered to patients from the later time cohort. The majority of patients in group 2 received taxanes (84.9%), compared to 71.8% in group 1 (P<0.01). Most patients in group 2 received taxanes in first line (67.8%), compared to only 16.8% in group 1 (p<0.001).

Trastuzumab was administered to all HER-2 positive patients from either group. But, as HER-2 status was more frequently known in group 2, the number of patients treated with trastuzumab was also much higher (n=38) than in group 1 (n=3) (Table 2). Capecitabine was administered to 69% patients in group 2, compared to only 4.7% in group 1 (P<0.001). Finally, 27 patients (18.1%) of group 1 received highdose chemotherapy with stem cell transplantation (HDCSCT) and their median age was 37 years, whereas none of group 2 patients received HDCSCT.

All patients of the entire cohort received at least one cure of chemotherapy in the hospital. We observed a significant increase in the use of oral chemotherapy (71.7% vs. 9.3%; P<0.001) and systemic treatments at home (32.2% vs. 2%; P<0.001) over time.

Costs of chemotherapy drugs

Not surprisingly, the total costs of chemotherapy nearly tripled over time. The overall costs of chemotherapy drugs for the entire cohort (n=301) were estimated to be 5,209,771 €, breaking down into 1,321,023 € for group 1 and 3,848,748 € for group 2. Thus, the median costs of chemotherapy drugs per patient increased from 6,272 € in group 1 to 13,035 € in group 2 (P<0.001; Table 4).

Up to progression, the median cost of metastatic breast cancer chemotherapy per patient and per year was 3,167 €. It appeared to be higher in group 2 (4,864 €) than in group 1 (2,273€). As regards costs according to the LOC, the median cost of a LOC was significantly higher in group 2 (3,306 €) than in group 1 (1,005 €; P<0.001)

(table 5).
Trastuzumab, docetaxel and paclitaxel were responsible for 66.7% of the total costs of chemotherapy (Table 6). As expected, trastuzumab was the most expensive drug, with a total of 1,800,007 €, corresponding to 36.35% of the overall costs. With only 43 patients treated with trastuzumab in the entire cohort, the median cost per patient was 43,721 €. The second most expensive molecule was docetaxel, with a total cost of 1,193,386 €, corresponding to 22.9% of the total expenditures. The median cost of docetaxel per patient was 6,521 €. The third most expensive molecule was paclitaxel, with a total cost of 402,163 €, corresponding to 7.7% of the total expenditures. The median cost of paclitaxel per patient was 4,278 €.

Survival of metastatic breast cancer patients treated by chemotherapy

The median OS of the entire cohort was 2.75 years. The survival of MBC patients treated by chemotherapy did not change between the two cohorts (Figure 1A), with a 3-years OS rate estimated to 41% in the 1994-1998 group and 44% in the 2003-2006 group (P=0.52). Interestingly, we observed higher 5-years survival rate in the second group (28%) in comparison to the first one (16%). Most of long surviving patients (> 5 years) in group 2 had hormone receptor positive tumors (73%) and only two of them were HER-2 positive.

Univariate analysis of survival showed that the presence of HR, a progression-free interval >2 years, bone metastases and the administration of anthracyclines in first line were associated with improved OS. In contrast, multiple metastases, soft tissue metastases, visceral metastases and performance status >1 were associated with poor outcome (Table 3).

All patients with a positive HER-2 status (n=41) received at least one line of chemotherapy with trastuzumab used alone or combined with other drugs.

Interestingly, for patients with known HER-2 status (n=131), positivity was not associated with worse survival (HR=0.99, P=0.99; Figure 2). When only patients with HR-positive tumors were considered (n=172), the median OS was 3.15 years in patients treated by chemotherapy between 2003 and 2006 and 2.54 years for those treated between 1994 and 1998, but this difference was not statistically significant (P=0.13, Figure 3). As expected, a multivariate analysis adjusted on the patient cohort showed that single metastatic site, bone metastases and HR were prognostic factors for survival (Table 4).

Discussion

Although clinical trials suggest that some advances have been made in the management of MBC over the last two decades, it is not clear whether the survival of these patients has improved in the context of daily practice. The major new chemotherapy drugs were approved after 1994 and this date became a turning point in cancer treatment. One of the objectives of our work was to study the evolution of clinical practice in the treatment of MBC with chemotherapy during the last 15 years.

The first period (1994)(1995)(1996)(1997)(1998) was chosen because it corresponds to the introduction of taxanes in MBC.; paclitaxel was approved in France in 1994 and docetaxel in HER-2 status was virtually unknown in the quasi-totality of the first group patients.

This analysis was generalized in the early 2000's with the generalization of administration of trastuzumab to patients with positive HER-2 status. Similarly, hormone receptors (HR) status was more frequently known in group 2 than group 1 whereas hormone therapies in the metastatic setting was prescribed to the majority of patients of group 1, including some patients with negative HR. Until the end of the 1990's, hormone therapies could be administered to patients independently of HR status [START_REF]Randomized trial of two versus five years of adjuvant tamoxifen for postmenopausal early stage breast cancer. Swedish Breast Cancer Cooperative Group[END_REF]. The publication of a meta-analysis of clinical trials evaluating tamoxifen [START_REF]Tamoxifen for early breast cancer: an overview of the randomised trials. Early Breast Cancer Trialists' Collaborative Group[END_REF] showed that positive HR is a predictive factor of response and changed clinical practice.

Recent studies have investigated the costs of expensive drugs like trastuzumab [START_REF] Matter-Walstra | Trastuzumab beyond progression: a cost-utility analysis[END_REF][START_REF] Poncet | Treatment of metastatic breast cancer: a large observational study on adherence to French prescribing guidelines and financial cost of the anti-HER2 antibody trastuzumab[END_REF][START_REF] Perez-Ellis | Cost-Effectiveness Analysis of Trastuzumab (Herceptin) in HER2-Overexpressed Metastatic Breast Cancer[END_REF] and taxanes [START_REF] Benedict | An economic evaluation of docetaxel and paclitaxel regimens in metastatic breast cancer in the UK[END_REF] or the total costs of chemotherapy [START_REF] Paviot | Impact of the chemotherapy protocols for metastatic breast cancer on the treatment cost and the survival time of 371 patients treated in three hospitals of the Rhone-Alpes region[END_REF] but, to our knowledge, this is the first study describing the evolution of expenditures associated with all the chemotherapy drugs prescribed in the context of daily clinical practice. Our study was motivated by the fact that the costs of chemotherapeutic drugs have one of the highest growth rates. In France, the French drug agency (AFSSAPS) estimated this increase to be 23% per year in 2006 [START_REF] Affssaps | Les ventes de médicaments aux officines et aux hôpitaux en France Chiffres-clés[END_REF]. Overall, we observed an increase in the administration of expensive drugs such as trastuzumab, taxanes and capecitabine, and a significant reduction in the administration of "old drugs", i.e. anthracyclines and vinorelbine, to MBC patients. Consequently, the total costs of chemotherapy nearly tripled while the median number of lines of chemotherapy remained stable. This increase in costs was mainly due to the two molecules described above, trastuzumab and docetaxel, which were responsible for more than half of expenditures. Our observations are in accordance with those reported by the French drug agency since these two molecules were the most important cost drivers for hospital pharmacies in 2006 in France [START_REF] Affssaps | Les ventes de médicaments aux officines et aux hôpitaux en France Chiffres-clés[END_REF]. Although trastuzumab is responsible for 36% of the total costs of chemotherapy, in our cohort it beneficially altered the natural history of women with HER-2 positive MBC by leveling out outcome differences with women with HER-2 negative disease.

Our study has revealed no significant difference in overall survival rate at 3 years between the two periods of time. Nevertheless, it is important to note that this survival was longer than reported in most published series [START_REF] Chia | The impact of new chemotherapeutic and hormone agents on survival in a population-based cohort of women with metastatic breast cancer[END_REF][START_REF] Andre | Breast cancer with synchronous metastases: trends in survival during a 14-year period[END_REF]. Recent retrospective studies have shown a trend toward improved survival in MBC patients [START_REF] Chia | The impact of new chemotherapeutic and hormone agents on survival in a population-based cohort of women with metastatic breast cancer[END_REF][START_REF] Andre | Breast cancer with synchronous metastases: trends in survival during a 14-year period[END_REF][START_REF] Giordano | Is breast cancer survival improving?[END_REF][START_REF] Arveux | Breast cancer survival in France: A relative survival analysis based on 68,449 cases treated in the 20 French comprehensive cancer centers between 1980 and 1999[END_REF] but none has clearly demonstrated a relationship with new chemotherapeutic drugs. Herein, we observed a tendency toward increased survival rate at 5 years in group 2 patients' and most of these long-surviving patients had hormone positive tumors, suggesting a benefit from new hormonal therapies.

Several hypotheses could explain the absence of survival improvement in our study.

First, the median number of lines of chemotherapy was similar and equal to three in the two groups, which is higher than reported in the literature [START_REF] Andre | Breast cancer with synchronous metastases: trends in survival during a 14-year period[END_REF]. Second, we observed similarities between the two major chemotherapeutic drugs used in MBC, i.e. anthracyclines and taxanes, which were administered to the majority of patients in the two groups. Thus taxanes were extensively used in both cohorts, all lines included. Data showing improvement of OS with the use of taxanes in advanced breast cancer came from trials comparing populations with exposure to taxanes to those with limited exposure (limited cross-over) [START_REF] Nabholtz | Prospective randomized trial of docetaxel versus mitomycin plus vinblastine in patients with metastatic breast cancer progressing despite previous anthracycline-containing chemotherapy. 304 Study Group[END_REF]. As a consequence, this fact does not allow entertaining any potential impact of taxanes on OS between the 2 cohorts.

Third, the major difference between the two periods of time was the introduction of trastuzumab and capecitabine. Trastuzumab was given only to the sub-group of patients with positive HER-2 status, who represent no more than 25% of all MBC patients [START_REF] Owens | HER2 amplification ratios by fluorescence in situ hybridization and correlation with immunohistochemistry in a cohort of 6556 breast cancer tissues[END_REF]. The benefit of this drug is expected to be limited to this population [START_REF] Slamon | Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2[END_REF].

In our study, the sub-group of HER-2 positive patients treated with trastuzumab actually benefited from this drug since their survival was equal to that of patients with negative HER-2 status, a cohort historically considered to be associated with better prognosis. These observations are in accordance with recent reports [START_REF] Dawood | Prognosis of women with metastatic breast cancer by HER2 status and trastuzumab treatment: an institutional-based review[END_REF]. Thus, trastuzumab has definitively an effect on OS of patients with positive HER-2 status, but this beneficial impact is diluted in our study due to the small percentage of these patients among total MBC population. Capecitabine has only a modest potential benefit in terms of overall survival, as shown in the registration trial [START_REF] Seidman | Single-agent capecitabine: a reference treatment for taxane-pretreated metastatic breast cancer?[END_REF]. Moreover, the compliance of patients to this oral agent is certainly an issue to be addressed in the context of potential impact on OS.

Interestingly, we observed a trend toward improved survival over time in patients with HR-positive tumors. This is probably related to the use of new hormonal therapies approved for MBC patients during the last decade such as aromatase inhibitors [START_REF] Gibson | Aromatase inhibitors for treatment of advanced breast cancer in postmenopausal women[END_REF] and LH-RH agonists combined with tamoxifen [START_REF] Klijn | Combined treatment with buserelin and tamoxifen in premenopausal metastatic breast cancer: a randomized study[END_REF][START_REF] Klijn | Combined tamoxifen and luteinizing hormone-releasing hormone (LHRH) agonist versus LHRH agonist alone in premenopausal advanced breast cancer: a metaanalysis of four randomized trials[END_REF]; these drugs have demonstrated a significant survival benefit over other endocrine therapies.

Our study has many limitations. It is a retrospective study conducted in a tertiary care institution with biases that do not allow drawing any general reliable conclusions on the impact of modern chemotherapies and trastuzumab on survival of MBC patients.

The two cohorts are small and consequently lack statistical power. This small sample size introduces some concerns in the context of an extremely heterogeneous malignancy like breast carcinoma.

Our medico-economic study also has many limitations. First, we only evaluated the costs of MBC chemotherapy drugs, and we did not explore other direct and indirect costs, principally hospitalization costs which probably decreased with the extensive use of outpatient hospitalization and the development of cancer supportive treatments like biphosphonates and G-CSF. Indeed, 18% of group 1 patients received HDCSCT. In this case, the costs of chemotherapy drugs were clearly negligible compared to the total costs of the procedure [START_REF] Rosa | Costs of high-dose chemotherapy and peripheral blood progenitor cell autograft for breast cancer[END_REF]. Second, we used 2008 prices, not the prices in effect when the drugs were administered. As the prices of certain drugs like taxanes and trastuzumab have changed over the last decade, this could have an impact on the calculation of total costs. Third, we did not evaluate the quality of life of the patients included in our cohort, because the study was retrospective. Nevertheless, our results confirm the important increase over time of expenditures related to chemotherapy drugs [START_REF] Halbert | Outpatient cancer drug costs: changes, drivers, and the future[END_REF]. In MBC, the part of chemotherapy in the total pharmaceutical costs has grown from 10% to 26% between 1988 and 2000 [START_REF] Levy | The cost of chemotherapy][END_REF] and this evolution has probably accelerated since the approval of new expensive targeted therapies such as trastuzumab, lapatinib and bevacizumab.

There is a growing consensus worldwide that cost-effectiveness considerations should be taken into account when making private or public health insurance decisions regarding the coverage of innovative and costly medical procedures [START_REF] Garber | Cost-effectiveness and evidence evaluation as criteria for coverage policy[END_REF].

As the median survival of MBC patients does not exceed 3 years, a cost-utility study evaluating both the costs of treatment and patient quality of life in a large prospective and multicentric study, i.e. the French federation of cancer centers, with control of major outcome predictors could be useful in order to draw the appropriate conclusions.

Tables and Figures

  Inclusion criteria included histological or cytological evidence of breast cancer, but a biopsy of the metastasis was not required. Based on the timing of the development and dissemination of anti-MBC chemotherapeutic agents, we defined two time cohorts, 1994-1998 (group 1) and 2003-2006 (group 2). Any patient diagnosed with MBC (either primary tumor or first recurrence of distant metastases) and treated with chemotherapy could be included in these time cohorts. Patients in group 1 must have received their first cure of chemotherapy between January 1 st 1994 and December 31 st 1998. Patients in group 2 must have received their first cure of chemotherapy between January 1, 2003 and December 31, 2006. Group 1 was used as the baseline comparator and corresponded to the introduction of taxanes (paclitaxel and docetaxel). Group 2 corresponded to the period when trastuzumab and capecitabine became available. Prior endocrine therapy for metastatic disease was allowed. The institutional review board approved the acquisition and report of the data from these patients.

  1998. The second period(2003)(2004)(2005)(2006) corresponds to the routine use of trastuzumab and capecitabine, respectively approved in 2000 and 2002. , HER-2 status and prior exposure to major chemotherapeutic agents. Age difference is probably due to two principal causes.First, the majority of old patients (older than 70 years) with MBC did not receive chemotherapy in the early 1990's because of the poor tolerability of available drugs and the lack of supportive therapies. Most of these patients received hormone therapies when indicated or palliative care. Second, in the 1990's, several clinical trials testing HDCSCT were ongoing at the Centre Léon Bérard[START_REF] Biron | Pegase 03: a prospective randomized phase III trial of FEC with or without high-dose thiotepa, cyclophosphamide and autologous stem cell transplantation in firstline treatment of metastatic breast cancer[END_REF][START_REF] Bachelot | A phase I/II study of 4 monthly courses of high-dose cyclophosphamide and thiotepa for metastatic breast cancer patients[END_REF][START_REF] Lotz | High-dose chemotherapy with haematopoietic stem cell transplantation for metastatic breast cancer patients: final results of the French multicentric randomised CMA/PEGASE 04 protocol[END_REF] and these trials included only young patients (younger than 50 years). In our study, 27 patients treated in group 1 received HDCSCT and their median age was 37 years.

Figure 1 :

 1 Figure 1: Overall survival of metastatic breast cancer patients according to the

Figure 2 :

 2 Figure 2: Overall survival of metastatic breast cancer patients according to

Figure 3 :

 3 Figure 3: Overall survival of metastatic breast cancer patients with positive

  Figure 1 &OLFN KHUH WR GRZQORDG )LJXUH ILJXUH SSW

Figure 2 &OLFN

 2 Figure 2 &OLFN KHUH WR GRZQORDG )LJXUH ILJXUH SSW

Figure 3 &OLFN

 3 Figure 3 &OLFN KHUH WR GRZQORDG )LJXUH ILJXUH SSW

Table 1 :

 1 Baseline demographics of the two time groups. SCT: stem cell transplantation

Table 2 : Lines of chemotherapy (LOC) administered in the metastatic settingTable 3 :

 23 Univariate analysis of overall survival (OS). CI: Confidence Interval, HR:Hazard Ratio, SBR: Scarff Bloom and Richardson score.

Table 4 : Multivariate analysis of overall survival adjusted to the group of patients

 4

. HR: Hazard Ratio; 95% CI: 95% Confidence Interval

Table 5 : Costs of lines of chemotherapy according to patient group.

 5

*: patient included in a clinical trial

Table 6 : Costs of the three most expensive chemotherapy drugs according to patient group.

 6

Table 3 1 2

 32

		1
				Group 1 (1994-1998)	Group 2 (2003-2006)	P
					n=149		n=152
	Median age at diagnosis of MBC, years	49		55
	50 > 50		82 67	(55%) (67%)	51 101	(35.6%) (66.5%)	<0.001
	Median disease-free interval, years		2.29	2.14
	2 >2		67 82	(45%) (55%)	70 82	(46%) (54%)	NS
	Number of metastatic sites
	1	2		88 61	(59%) (41%)	86 66	(57.3%) (42.7%)	NS
	Sites of metastases
	Bone		86	(57.7%)	85	(56%)
	Viscera Soft tissue	84 35	(56.4%) (23.5%)	86 29	(56.6%) (19.1%)	NS
	Other		7	(4.7%)	9	(6%)
	Performance status
	0-1		147	(98.7%)	147	(96.7%)
		2		2	(1.3%)	4	(2.6%)	NS
	Unknown	0		1	(0.7%)
	Hormone receptor status
	Positive		84	(56.4%)	88	(57.9%)
	Negative	33	(22.1%)	56	(36.8%)	<0.001
	Unknown	32	(21.5%)	8	(5.3%)
	HER-2 status
	Positive Negative	2 6	(25%) (75%)	39 84	(25.7%) (68.3%)	NS
	Unknown	141		29
	Synchronous metastases
	Yes No		29 120	(19.5%) (79.5%)	33 119	(21.7%) (78.3%)	NS
	Adjuvant chemotherapy
	Yes		88	(73.3%)	91	(76.5%)	NS
	No		32	(26.7%)	28	(23.5%)
	Type of adjuvant chemotherapy
	Anthracyclines
	Yes No		77 43	(64.2%) (35.8%)	87 32	(72.5%) (27.5%)	NS
	Taxanes
	Yes No		1 119	(0.8%) (99.2%)	18 101	(15.1%) (84.9%)	<0.001
	Adjuvant hormone therapy
	Yes		84	(70%)	64	(53.8%)
	No		29	(24.2%)	54	(45%)	<0.001
	Unknown	7	(5.8%)	1	(8.3%)
	Hormone therapy at metastatic stage
	Yes No		135 12	(90.6%) (8%)	93 59	(61.2%) (38.8%)	<0.001
	Unknown	2	(1.4%)	0
	High-dose chemotherapy with SCT at
	metastatic stage
	Yes		27	(18.1%)	0		<0.001
	No		122	(81.9%)	152	(100%)
		2	Table 1
		3

Table 4 Group 1

 41

					(1994-1998)		Group 2 (2003-2006)
					(n=149)			(n=152)
				Median	Minimum	Maximum	Median	Minimum	Maximum	p
	Total	cost	of
	chemotherapy	drugs	6,272	20	189,923	13,035	11	162,960	<0.001
	per patient (€)
	Cost of 1 st line (€)		1,269	1.50	12,994	5,744	11	137,074	<0.001
	Cost of 2 nd line (€)	1,421	0*	18,900	2,625	0*	53,564	<0.001
	Cost of 3 rd line (€)		1,074	0.40	14,484	2,315	0*	30,509	<0.001

Table 5 Group 1

 51

			(1994-1998)		Group 2 (2003-2006)
		Number of			Number of
		patients	Total costs (€)	% of costs	patients	Total costs (€)	% of costs
		(%)			(%)
	Trastuzumab	3 (2%)	153,037	11.6	40 (26.3%)	1, 726,970	44.8
	Docetaxel	94 (63%)	623,840	47.2	89 (58.6%)	569,546	14.7
	Paclitaxel	22 (14.7%)	103,891	7.8	72 (47.4%)	298,273	7.7

Table 6

 6

Aknowledgements 1

The authors acknowledge Mrs Marie-Dominique Reynaud for editorial assistance.


Corina J G Hurk

Renate Eckel

Lonneke V Poll-Franse

Willem W Coebergh

Johan W R Nortier

Dieter Hölzel

Wim P M Breed

Jutta Engel

Corina J G Van Den Hurk

Lonneke V Van De Poll-Franse

Jan Willem

Dieter Holzel

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d

Keywords: metastases pattern, time to metastases, survival, breast cancer

enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Unfavourable pattern of metastases in M0 breast cancer patients during 1978-2008: a population-based analysis of the Munich Cancer Registry

INTRODUCTION

The prevalence of breast cancer patients without metastases at diagnosis (M0) has increased in industrialised countries. This increase can be explained by the rising incidence and decreasing overall mortality rate of breast cancer [START_REF] Louwman | On the rising trends of incidence and prognosis for breast cancer patients diagnosed 1975-2004: a long-term population-based study in southeastern Netherlands[END_REF][START_REF] Jatoi | Breast cancer mortality trends in the United States according to estrogen receptor status and age at diagnosis[END_REF][START_REF] Breast | Collaborative Group: Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials[END_REF][START_REF] Gondos | Recent trends in cancer survival across Europe between 2000 and 2004: A model-based period analysis from 12 cancer registries[END_REF], which is attributed to earlier detection and therefore advantageous stage distribution, and improvements in treatment. [START_REF] Louwman | On the rising trends of incidence and prognosis for breast cancer patients diagnosed 1975-2004: a long-term population-based study in southeastern Netherlands[END_REF] The early detection is largely due to breast cancer screening, developments in imaging and higher awareness of the disease among women. One would expect that these developments would influence the occurrence of metastases at diagnosis and in follow-up.

The reported percentage of M0 patients with metastases in follow-up is 20% to 30%. [START_REF] Breast | Collaborative Group: Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials[END_REF] The proportion of patients with metastases at initial diagnosis (M1) remains stable at about 5% [START_REF] Louwman | On the rising trends of incidence and prognosis for breast cancer patients diagnosed 1975-2004: a long-term population-based study in southeastern Netherlands[END_REF][START_REF] Edwards | Improvement in the prognosis of breast cancer from 1965 to 1984[END_REF] or decreases minimally. [START_REF] Jensen | Trends in breast cancer during three decades in Denmark: stage at diagnosis, surgical management and survival[END_REF] In M1 patients, patterns of metastases and survival are frequently described, but the progression patterns and time trends of occurrence of metastases after initial treatment in M0 patients are seldom investigated. The objective of this study was to describe the incidence of metastases and survival after metastases in M0 breast cancer patients since 1978. Therefore, this study will provide knowledge about the level of progress in medical management of metastases in these patients. Data were obtained from the Munich Cancer Registry (MCR), which uniquely documents metastases during followup. [START_REF] Schlesinger-Raab | Metastatic renal cell carcinoma: results of a population-based study with 25 years follow-up[END_REF]

PATIENTS AND METHODS

Study population and data collection

Data on breast cancer patients diagnosed in the period 1978-1984, 1985-1994 and 1995-2003 were obtained from the population-based MCR. The MCR has in the last period a catchment area of 2.5 million residents (since 2002 3.9 million residents) and records data on all patients newly diagnosed with cancer. [START_REF] Engel | The process of metastasisation for breast cancer[END_REF][START_REF] Curado | Cancer Incidence in Five Continents[END_REF] The unequal subdivision into time periods of initial diagnosis marks steps in the changes from a hospital-based (up to 1984) to a populationbased registry of Munich and surrounding area's. The MCR is for breast cancer population-based since 1994, when the pathologists of the region started structural cooperation with the MCR. Data on primary diagnosis and progression were provided by the hospitals in the Munich region by means of tumour-specific reporting forms, doctors' letters and pathology reports and nowadays also through online documentation. Diagnosis of metastases was based on radiological imaging, physical evaluation or histological examination in regular oncological follow-up. Life status information was obtained from the population registration offices and death certificates until October 1 st 2007 and is complete for more than 90% of patients. [START_REF] Schlesinger-Raab | Metastatic renal cell carcinoma: results of a population-based study with 25 years follow-up[END_REF] In the Munich catchment area screening for breast cancer has increased over time since the beginning of the 1990s, was initially opportunistic and at the end widespread, before programmed screening was started in 2004.

Between 1978 and 2003, the MCR registered 36,002 female patients diagnosed with primary invasive breast cancer. The data set did not include patients with secondary malignancies or sarcomas or with only a death certificate. Follow-up was complete up to October 30, 2008.

Statistical analysis

Statistical analyses included time to metastases within 5 years of initial diagnosis and survival following the first metastasis among patients who developed a metastasis within 5 years of initial diagnosis. Metastases were included in the analyses grouped by the most frequent sites of occurrence or combinations of these specific sites. These combinations were independent of sequence of metastatic sites and synchronous or metachronous detection and were only inserted if no additional metastases were present at rarer sites. Loco regional skin or lymph node recurrences were excluded. Event-free patients were censored on October 30 2008 and patients who were lost to follow-up at their last date of contact. Survival times, time to metastases and survival after metastases were described with the Life- Additional variables for survival following metastases were time to metastases and site(s) of metastases. When evaluating the proportional hazard assumption of the main objective of this study, namely period of diagnosis, the graphs of the survival function versus the survival time yielded parallel curves as did the graphs of the log(-log(survival)) versus log of survival time.

The SAS computer package (version 9.1) was used for all statistical analyses (SAS Institute Inc., Cary, NC, USA, 1999).

RESULTS

General characteristics of M0 patients

The MCR comprised 1). The incident number of patients approximately doubled each period and during follow-up 8183 (24%) patients developed a metastasis after M0 at diagnosis, 5490 (67%) of whom within 5 years of initial diagnosis. An increase in 5-year overall survival was observed for the last period (77% vs. 76% vs. 82%, p<0.0001) (Figure 1).

In time, the observed proportion of patients diagnosed with pT1 and lymph nodenegative tumours increased, as did the proportion of older women (70+) (Table 1). About 80% of patients had a tumour of the ductal type and positive ostrogen (ER) or progesteron (PR) receptors. Unknown receptor status decreased considerably from the second (46%) to the third study period (16%), while the ratio of positive to negative receptors hardly changed. The proportion of patients who underwent mastectomy decreased from 98% in the first to 35% in the last period and systemic treatment was used more often in recent periods (22% vs. 44% vs. 70%). A decrease in the proportion of patients undergoing radiotherapy was seen in period 1985-1994.

Patterns of metastases

In the cohort of 5490 M0 patients with metastases within 5 years of initial diagnosis, 59% developed the first metastasis within 2.5 years (Table 2). Overall 56% of the patients developed metastases at 2 or more sites and the proportion of metachronously diagnosed metastases increased in time from 66% to 82%. The proportion of bone metastases declined (69% vs. 62% vs. 47%) while the proportion of liver, central nervous system (CNS) and less common occurring sites of metastases increased. In time, trends were comparable for the first detected metastases. In the first period 85% of patients died within 5 years of the first metastases versus 95% in the last period. Of patients alive or lost to follow-up, median followup was 29 months in the first period, 11 months in 1985 to1994 and 50 months in 1995-2003.

Patients who developed metastases within 5 years had a positive lymph node status at initial diagnosis more often and had a higher pT status than M0 patients in general.

Time from diagnosis to first metastasis

The proportion M0 patients who developed metastases within 5 years of initial diagnosis declined significantly from 27% in 1978-1984 to 15% in 1995-2003 (p<0.0001) (Figure 2a).

Overall, the risk of occurrence of metastases was highest in the first 2.5 years of initial diagnosis (65% vs. 60% vs. 56%), as also indicated by the steepness of the curves in Figure 3. For the specified metastatic sites, only small differences emerged in time to detection during 5 years of follow-up, except for skin metastases that appeared later. Detection of metastases occurred within 5 years of initial diagnosis in 76% of patients who developed a combination of bone, liver and lung metastases and in 52% of patients with skin metastases only.

The hazard of developing metastases within 5 years of diagnosis was lowest in the most recent period (HR=0.50, p<0.001) (Table 3). A positive receptor status (HR=0.61, p<0.001) and the combination of chemotherapy and hormonal therapy (HR=0.69, p<0.001)

were associated with a lower risk of metastases. Age and radiotherapy were not significantly associated with the occurrence of metastases within 5 years.

Time from first metastasis to death

If only the death certificate or a post mortem report indicated metastases, the date of first metastasis was similar to the date of death and these patients were excluded from survival analyses (n=6251).

In M0 patients with metastases within 5 years of initial diagnosis, 5-year actuarial survival rates after occurrence of first metastasis decreased and differed significantly between the time periods (17% vs. 12% vs. 8%, p=0.0001) (Figure 2b).

Multivariate regression analysis showed that patients who developed a metastasis within 5 years of diagnosis in the period 1985-1994 had a 20% increased hazard of dying compared to those in 1978-1984 and 1995-2003; this first and last period showed no difference in survival (Table 4). However, when site of metastases was removed from the model, then the hazard ratios became 1.24 (p=0.003) and 1.21 (p=0.02) for the last two periods. Mortality risk increased with the increase in age and a higher pT, positive lymph nodes and differentiation grade. The hazard of dying for patients with metastases was 35% lower for receptor status-positive patients and decreased 7% in each additional year between initial diagnosis and first metastasis.

Prognosis for patients after metastases varied for the site(s) of metastasis (Table 3).

Up to 5 years after detection of metastases, patients with bone metastases or skin metastases alone exhibited best survival (Figure 5). From 5 to 10 years, skin alone and distant lymph node alone had best prognosis up to 10 years after detection of metastases (data not shown).

DISCUSSION

In the period 1978-2008, the hazard of developing metastases during follow-up decreased markedly and overall survival improved among women diagnosed with M0 breast cancer.

Concurrently, we observed a change in the anatomic pattern of metastasis, without improvement in survival after occurrence of these metastases. There might be several explanations for our observations.

We attribute the generally improved survival of M0 patients in the last period to adjuvant, especially hormonal, treatment which was routinely administered at that time. In addition, patients recorded by the MCR showed advantageous stage distribution over the periods, which also contributed to improved prognosis. Time from initial diagnosis to metastasis is prolonged for pT1 versus pT2 [START_REF] Engel | The process of metastasisation for breast cancer[END_REF], but changes in adjuvant systemic treatment will also have lengthened the time. [START_REF] Johansson | Improved survival for women with stage I breast cancer in south-east Sweden: a comparison between two time periods before and after increased use of adjuvant systemic therapy[END_REF][START_REF] Toi | Risk reduction of distant metastasis in hormonesensitive postmenopausal breast cancer[END_REF] The adjuvant treatment prevents the development of metastases or at least postpones it. However, if dormant tumour cells start growing again, whether due to resistance against the continued systemic therapy or not, then the survival time of the metastasized patients remained as poor as before. Over time, the proportional anatomic distribution of metastasis shifted from bone, with long survival times, towards CNS and liver, which are much more lethal. This shift has also been reported by others, but only for the first site of metastasis. [START_REF] Yerushalmi | Patterns of relapse in breast cancer: changes over time[END_REF] The increased use of hormonal treatment might cause the shift since ER-positive tumours tend to metastasize to bone, ER and PR negativity are commonly associated with visceral metastases, especially liver and CNS. [START_REF] Coleman | Clinical course and prognostic factors following bone recurrence from breast cancer[END_REF][START_REF] Blanco | Prognostic factors in recurrent breast cancer: relationships to site of recurrence, disease-free interval, female sex steroid receptors, ploidy and histological malignancy grading[END_REF][START_REF] Solomayer | Metastatic breast cancer: clinical course, prognosis and therapy related to the first site of metastasis[END_REF][START_REF] Pestalozzi | Identifying breast cancer patients at risk for Central Nervous System (CNS) metastases in trials of the International Breast Cancer Study Group (IBCSG)[END_REF][START_REF] Smid | Genes associated with breast cancer metastatic to bone[END_REF][START_REF] Kamby | The pattern of metastases in human breast cancer: methodological aspects and influence of prognostic factors[END_REF] The increased proportion of CNS metastases might also reflect improvement in adjuvant systemic treatment;

CNS is regarded as a sanctuary site, that is less affected by most therapeutics than other sites. [START_REF] Duchnowska | Central nervous system metastases in breast cancer patients administered trastuzumab[END_REF] In this study liver metastases, alone or in combination, occurred earliest during follow-up and were like CNS metastases, the most lethal. So, the largest benefit in the survival of patients with breast cancer will most likely come from the prevention and better treatment of CNS and liver metastases. In patients with over expression of HER2 major improvements have been reached with trastuzumab [START_REF] Mannocci | Use of trastuzumab in HER2-positive metastatic breast cancer beyond disease progression: a systematic review of published studies[END_REF] and recently lapatinib. [START_REF] Curran | Lapatinib: in postmenopausal women with hormone receptor-positive, HER2-positive metastatic breast cancer[END_REF][START_REF] Arslan | Systemic treatment in breast-cancer patients with brain metastasis[END_REF] Bisphosphonates of the third generation seem to have also an anti-tumour effect in the adjuvant setting. [START_REF] Reeder | The role of bisphosphonates in the adjuvant setting for breast cancer[END_REF] In addition poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors are likely to be beneficial for patients with triple negative tumours. [START_REF] Underhill | A review of PARP inhibitors: from bench to bedside[END_REF] Therefore, the incidence and pattern of metastases will change further in the future. Overall, sites of metastases appeared to contribute largely to the period effect, since exclusion of site of metastases in the multivariate analysis increased the mortality hazard ratio for the last versus the first period to 21%.

Unfortunately, no information was available about the type of treatment of the metastasized cancer in the MCR region.

The worse outcome after occurrence of metastases in patients without metastasis at diagnosis might be related to less sensitive tumour cells that developed resistance after adjuvant systemic therapy. This is supported by recent observations of M1 patients who, in particular when the primary tumour had been removed completely, had a more favourable prognosis compared to M0 patients with subsequent metastases. [START_REF] Coleman | Clinical course and prognostic factors following bone recurrence from breast cancer[END_REF][START_REF] Engel | Determinants and prognoses of locoregional and distant progression in breast cancer[END_REF][START_REF] Jimeno | Initially metastatic breast carcinoma has a distinct disease pattern but an equivalent outcome compared with recurrent metastatic breast carcinoma[END_REF][START_REF] Rapiti | Complete excision of primary breast tumor improves survival of patients with metastatic breast cancer at diagnosis[END_REF][START_REF] Schlesinger-Raab | Metastasiertes Mammakarzinom: Keine Lebensverlangerung seit 20 Jahren[END_REF] However, contradictory results have been reported of M1 patients, who sometimes had worse survival compared to M0 patients who developed metastases in follow-up. [START_REF] Andre | Breast cancer with synchronous metastases: trends in survival during a 14-year period[END_REF][START_REF] Smigal | Trends in breast cancer by race and ethnicity: update 2006[END_REF][START_REF] Wilcken | Chemotherapy in metastatic breast cancer: A summary of all randomised trials reported 2000-2007[END_REF][START_REF] Ernst | Trends in the prognosis of patients with primary metastatic breast cancer diagnosed between 1975 and 2002[END_REF] Higher incidence of more aggressively growing tumours might be an additional explanation of the unimproved survival after metastases, since the increasing use of breast cancer screening mainly eliminates the slowly growing tumours. This is also reflected by the highly significant relationship between time to first metastasis and survival after occurrence of metastases, which remained after correction for period of diagnosis and site(s) of metastases.

More aggressive growth might also be partly attributed to the lack of effective therapies for aggressive subtypes of breast cancer, such as triple-negative, non-basal and basal-like subtypes. [START_REF] Lin | Sites of distant recurrence and clinical outcomes in patients with metastatic triple-negative breast cancer: high incidence of central nervous system metastases[END_REF] These subtypes are known to influence the growth rate, site of metastases, time to occurrence and survival after metastases. [START_REF] Yerushalmi | Patterns of relapse in breast cancer: changes over time[END_REF][START_REF] Kennecke | Metastatic behavior of breast cancer subtypes[END_REF] In this study the majority of metastases became manifest within 2.5 years of initial diagnosis, as observed by others. [START_REF] Toi | Risk reduction of distant metastasis in hormonesensitive postmenopausal breast cancer[END_REF][START_REF] Coleman | Clinical course and prognostic factors following bone recurrence from breast cancer[END_REF][START_REF] Elder | Patterns of breast cancer relapse[END_REF][START_REF] Mansell | Patterns and predictors of early recurrence in postmenopausal women with estrogen receptor-positive early breast cancer[END_REF] The MCR hosts unique data on clinically evident metastases in follow-up, but the prevalence of metastases in the MCR is slightly underdocumented. Surgically treated and histopathologically confirmed metastases are obtained from pathology reports and are therefore nearly complete. However, not histopathologically confirmed metastases will be documented in about 70% of cases, based on estimations of tumour-specific survival and relative survival, that should equalize the proportion of metastases. [START_REF] Schlesinger-Raab | Metastatic renal cell carcinoma: results of a population-based study with 25 years follow-up[END_REF]37] Some of the metastases are likely to remain unreported by physicians to the MCR and some might never be detected because there were no clinical manifestations before death. The MCR's completeness is difficult to check with literature, while proportions of metastatic sites in breast cancer vary considerably, both within clinical and within autopsy studies. [START_REF] Kamby | The pattern of metastases in human breast cancer: methodological aspects and influence of prognostic factors[END_REF][START_REF] Jimeno | Initially metastatic breast carcinoma has a distinct disease pattern but an equivalent outcome compared with recurrent metastatic breast carcinoma[END_REF][START_REF] Manders | Clinical management of women with metastatic breast cancer: a descriptive study according to age group[END_REF][START_REF] Hess | Metastatic patterns in adenocarcinoma[END_REF][START_REF] Perez | Bone-only versus visceral-only metastatic pattern in breast cancer: analysis of 150 patients. A GOCS study[END_REF][START_REF] Giordano | Is breast cancer survival improving? Trends in survival for patients with recurrent breast cancer diagnosed from 1974 through 2000[END_REF][START_REF] Lee | Breast carcinoma: pattern of metastasis at autopsy[END_REF][START_REF] Sanuki-Fujimoto | Pattern of tumor recurrence in initially nonmetastatic breast cancer patients: distribution and frequency of metastases at unusual sites[END_REF] Only a few studies were population-based, and the subdivision of metastatic sites and follow-up times differed. The most adequate comparisons should be based on patients with breast cancer as the cause of death. It is likely that for the period 1995-2003, data on metastases in the MCR were more complete and most representative, while at that time the database became approximately population-based. In time, methods of detection have improved and indications for diagnostics have changed, as exhibited by the decreased proportion of missing data on pT, pN and receptor status. In addition, the last period showed an increased number of metastases per patient, as well as increased detection of metastases at rarer sites.

Nevertheless, the observed change in pattern of metastases can be considered to be a mirror for general specialised care in a variety of hospitals, while there were no systematic or specific diagnostics for metastases in the MCR region.

In conclusion, the enhanced use and extensive developments in systemic treatment of patients with breast cancer might have prevented development of metastases in breast cancer. It changed the anatomic distribution of sites of metastases, but did not improve survival after occurrence of metastases. The most important reason seems to be the shift from bone metastases towards CNS and liver metastases. Furthermore, there might have been a

natural selection of more aggressively growing tumours in the recent period. So, at the time metastases became manifest, treatment possibilities remained insufficient, at least up to 2008.

It seems that therapies for liver and CNS metastases might yield the largest gains in survival of M0 breast cancer patients. And lastly, changes in patterns of metastases as a result of new treatments, illustrate the importance of including registration of metastases and secondary treatment in cancer registries. They can be used to study long term effects in the population and the usefulness of new treatment strategies.

TABLES AND FIGURES

Figure 1 . 5 -Figure 2a. 5 -Figure 2b .Figure 3 .*

 1552b3 Figure 1. 5-year overall survival of M0 breast cancer patients diagnosed between 1978 and 2003 (n=33771)

Figure 4 . 5 -*

 45 Figure 4. 5-Year survival after first metastasis in most common single sites and combinations of sites of metastases in M0 breast cancer patients with metastases within 5 years of diagnosis

Table 1 .

 1 Characteristics of M0 patients with breast cancer according to period of initial diagnosis (n=33,771)

	Characteristic			Period of initial diagnosis			P-value
		1978-1984	1985-1994	1995-2003**
		(n=4978)	(n=10,201)	(n=18,592)
		N	%*	N	%*	N	%*
	Median FU time after initial diagnosis
	of patients alive or lost to FU (mo)	148		177		80		<0.0001
	Deceased (1 Oct. 2008)	2893	(58)	5123	(50)	4571	(25)	<0.0001
	M0 at diagnosis, metastasis in FU	1785	(36)	2999	(29)	3399	(18)	<0.0001
	M0 at diagnosis, metastasis within 5
	years of FU	798	(16)	1159	(11)	1952	(10)	<0.0001
	Age (yrs)
	<50	1909	(38)	3522	(35)	4649	(25)
	50 -69	2380	(48)	4731	(46)	9540	(51)
	70+	689	(14)	1948	(19)	4403	(24)	<0.0001
	pT
	T1	978	(43)	4155	(47)	9358	(55)
	T2	958	(42)	3524	(40)	6224	(37)
	T3	202	(9)	436	(5)	723	(4)
	T4	149	(6)	693	(8)	747	(4)	<0.0001
	Unknown	2691	(54)	1393	(14)	1545	(8)***
	pN
	Negative	1071	(48)	4413	(52)	9649	(59)
	Positive	1142	(52)	4114	(48)	6682	(41)	<0.0001
	Unknown	2765	(56)	1674	(16)	2261	(12)
	Histological type
	Ductal	3533	(82)	7445	(80)	13970	(78)
	Lobular/Mixed	419	(10)	1486	(16)	3678
	Other/n.o.s.	363	(8)	346	(4)	276
	Unknown	663	(13)	924	(9)	668

Table 2 .

 2 Characteristics of M0 breast cancer patients with first metastasis within 5 years of initial diagnosis, according to period of initial diagnosis (n=5490)

	Characteristic			Period of initial diagnosis			P-value
		1978-1984	1985-1994	1995-2003
		(n=1214)	(n=1677)	(n=2599)
		N	%	N	%	N	%
	Metastasis within 2.5 years	791	(65)	999	(60)	1449	(56)	<0.0001
	Deceased within 5 years of first
	metastasis	1031	(85)	1484	(88)	2464	(95)	<0.0001
	Median FU time after initial
	diagnosis of patients alive or lost
	to FU (mo)	29		11		50		<0.0001
	Multiple synchronous	603	(50)	862	(51)	1592	(61)	<0.0001
	Multiple metachronous	399	(66)	637	(74)	1300	(82)	<0.0001
	Metastatic sites at first
	progression/ all metastases
	during follow-up*
	Bone	719 (60) /	838 (69)	881 (53) /	1047 (62)	980 (38) /	1226 (47)
	Lung	286 (24) /	376 (31)	372 (22) /	533 (32)	514 (20) /	783 (29)
	Liver	168 (14) /	286 (24)	266 (16) /	484 (29)	587 (23) /	961 (35)
	CNS	55 (5) /	123 (10)	81 (5) /	232 (14)	265 (10) /	630 (22)
	Skin	92 (8) /	149 (12)	109 (7) /	177 (11)	171 (7) /	290 (11)
	Distant lymph node	74 (6) /	104 (9)	189 (11) /	273 (16)	284 (11) /	413 (15)
	Other	164 (14) /	287 (24)	219 (13) /	427 (25)	630 (24) /	1267 (51)
	Total	1558 /	2163	2117 /	3173	3431 /	5579
	Mean number of metastases per
	patient	1.28 /	1.78	1.26 /	1.89	1.32 /	2.14
	Age (yrs)							<0.0001
	<50	506	(42)	653	(39)	723	(28)
	50 -69	576	(47)	794	(47)	1245	(48)
	70+	132	(11)	230	(14)	631	(24)
	pT							0.0004
	T1	132	(28)	411	(29)	612	(28)
	T2	234	(49)	688	(49)	1118	(51)
	T3	72	(15)	122	(9)	213	(10)
	T4	40	(8)	184	(13)	234	(11)
	Unknown (%)	736	(61)	272	(16)	422	(16)
	pN							0.9
	Negative	137	(30)	433	(31)	650	(31)
	Positive	320	(70)	949	(69)	1463	(69)
	Unknown (%)	757	(62)	295	(18)	486	(19)
	Receptor status (ER or PR)
	Negative	-	-	228	(29)	605	(30)	0.7
	Positive	-	-	562	(71)	1441	(70)
	Unknown (%)	-	-	887	(53)	553	(21)

Table 3 .

 3 Determinants of time to first metastasis in M0 breast cancer patients, within 5 years of initial diagnosis.

	Characteristics**	HR	HR*	95% CI	P-value
		Univariate	Multivariate
	Period of diagnosis
	1978-1984	1.00	1.00	-
	1985-1994	0.67	1.15	(0.98-1.35)	0.09
	1995-2003	0.39	0.50	(0.42-0.61)	<0.0001
	Age (yrs)
	<50	1.00	1.00	-
	50-69	0.83	0.98	(0.89-1.07)	0.7
	70+	0.82	0.98	(0.85-1.12)	0.7
	pT
	T1	1.00	1.00	-
	T2	1.60	1.80	(1.63-2.00)	<0.0001
	T3	2.21	1.84	(1.58-2.15)	<0.0001
	T4	2.98	2.32	(1.99-2.70)	<0.0001
	pN
	Negative	1.00	1.00	-
	Positive	3.29	2.11	(1.91-2.34) <0.0001
	Grade
	1	1.00	1.00	-
	2	6.20	3.60	(2.37-5.46)	<0.0001
	3/4	12.96	5.21	(3.43-7.91)	<0.0001
	Receptor status (ER/PR)
	Negative	1.00	1.00	-
	Positive	0.40	0.61	(0.55-0.69) <0.0001
	Histological type
	Ductal	1.00	1.00	-
	Lobulair	0.62	0.90	(0.79-1.02)	0.1
	Other	1.42	1.11	(0.90-1.38)	0.3
	Resection margins
	Negative	1.00	1.00
	Positive	1.84	1.37	(1.08-1.73)	0.009
	Unknown	2.48	1.59	(1.22-2.07)	0.0006
	Initial radiotherapy	0.75	0.94	0.86-1.02	0.1
	Initial systemic therapy
	No	1.00	1.00	-
	Chemotherapy	1.01 (NS)	0.95	(0.85-1.06)	0.4
	Hormonal therapy	0.50	0.92	(0.81-1.04)	0.2
	Both	0.47	0.69	(0.59-0.82)	<0.0001
	HR= hazard ratio, 95% CI= 95% confidence interval, ER= ostrogen receptor, PR=progesteron receptor
	NS= not significant

*variables included if univariately significantly associated **pT n=1867 missing, pN n=1959 missing, Differentiation grade n=2193 missing, Receptor status n=3046 missing, Resection margins n=4391 missing, Histological type n=533 missing.

Table 4 .

 4 Determinants of survival after first metastasis in M0 breast cancer patients with metastases within 5 years during follow-up 95% CI= 95% confidence interval, ER= ostrogen receptor, PR=progesteron receptor NS= not significant, CNS= central nervous system *variables included if they were univariate significantly associated **pT n=1334 missing, pN n=1413 missing, grade n=1720 missing, Receptor status n=2379 missing, site of metastases 'Other' n=2646. *** HR when site of metastases is excluded

	Characteristics* **	HR	HR***	95% CI	P-value HR	95% CI	P-value
		Univariate	Multi			Multi
			variate			variate
	Period of diagnosis
	1978-1984	1.00	1.00	-		1.00	-
	1985-1994	1.31	1.24	(1.08-	0.003	1.20	(1.04-1.38)	<0.01
	1995-2003	1.38	1.21	1.43)	0.02	1.08	(0.93-1.26)	0.3
				(1.04-
				1.40)
	Age (yrs)
	<50	1.00	1.00	-		1.00	-
	50-69	1.13	1.12	(1.04-	0.004	1.14	(1.05-1.24)	0.001
	70+	1.58	1.51	1.22)	<0.0001	1.57	(1.40-1.75)	<0.0001
				(1.34-
				1.69)
	pT
	T1	1.00	1.00	-		1.00	-
	T2	1.20	1.14	(1.05-	0.003	1.14	(1.04-1.24)	0.004
	T3	1.26	1.19	1.25)	0.01	1.19	(1.04-1.36)	0.01
	T4	1.46	1.23	(1.04-	0.003	1.22	(1.06-1.40)	0.004
				1.37)
				(1.07-
				1.41)
	pN
	Negative	1.00	1.00	-		1.00	-
	Positive	1.29	1.21	(1.12-	<0.0001	1.22	(1.13-1.33) <0.0001
				1.32)
	Grade
	1	1.00	1.00	-		1.00	-
	2	1.70	1.70	(1.21-	0.002	1.64	(1.17-2.31)	0.005
	3/4	2.39	2.17	2.40)	<0.0001	2.05	(1.46-2.89)	<0.0001
				(1.54-
				3.06)
	Receptor status (ER/PR)
	Negative	1.00	1.00	-		1.00	-
	Positive	0.58	0.62	(0.56-	<0.0001	0.65	(0.59-0.72) <0.0001
				0.69)
	Histological type
	Ductal	1.00	-			-
	Lobular	0.93 (NS)	-			-
	Other	1.03 (NS)	-			-
	Time to first metastasis****	0.91	0.93	(0.91-	<0.0001 0.93	(0.90-0.96) <0.0001
				0.96)
	Site(s) of Metastases
	Bone alone	1.00	-			1.00	-
	Liver alone	1.39	-			1.38	(1.15-1.67)	<0.0008
	Lung alone	1.09 (NS)	-			1.20	(0.97-1.47)	0.1
	CNS alone	3.16	-			2.81	(2.20-3.57)	<0.0001
	Skin alone	1.01(NS)	-			0.97	(0.71-1.33)	0.9
	Distant lymph nodes alone	1.13(NS)	-			0.94	(0.72-1.23)	0.6
	Liver, Bone	1.38	-			1.50	(1.25-1.79)	<0.0001
	Lung, Bone	1.28	-			1.18	(0.92-1.50)	0.2
	Bone, Liver, Lung	1.66	-				(1.33-2.10)	<0.0001
						1.67

****in years

All authors declared no conflicts of interest.