Dominic Fong
email: dominic.fong@i-med.ac.at

Michael Steurer

Richard Greil

Eberhard Gunsilius

Gilbert Spizzo

Guenther Gastl

Alexandar Tzankov

: E Gunsilius

Hodgkin lymphoma in Tyrol-a population-based study

Keywords: Hodgkin lymphoma, Population-based study, Tyrol, Hodgkin's disease

We aimed to analyze the epidemiology, clinical characteristics, and outcome of patients with Hodgkin lymphoma (HL) diagnosed in Tyrol. All patients with newly diagnosed HL between 1993 and 2005 were included in this study. Among the 158 cases included, nodular lymphocytic predominant HL (nodular paragranuloma) was identified in ten cases (6%) whereas the majority of patients had classical Hodgkin lymphoma. Age (p<0.01), sex (p=0.03), risk groups according to the German Hodgkin Study Group stratification (p<0.01), and bone marrow infiltration (p<0.01) were of prognostic significance considering overall survival (OS) whereas histological subtype and bulky disease were not. The 5-and 10-year OS rates for the total group were 89% and 85%, respectively. Notably, in patients with advanced-stage HL (n=49), combined modality treatment resulted in significantly better OS than chemotherapy alone (p=0.01). Three patients developed a second hematological malignancy and one patient developed breast cancer. However, five patients (3%) had a malignant hematological disorder before occurrence of HL. Concerning treatment-related toxicity, bleomycin-associated lung toxicity was observed in six (4%) patients and five (3%) developed lethal treatment-related infectious complications. Our results provide evidence that the incidence rate of HL in Tyrol is comparable to other Western countries. Modern risk-adapted treatment results in excellent long-term prognosis but may be complicated by serious nonhematological side effects, in particular, infections and bleomycin-induced lung toxicity. Furthermore, 3% of HL patients had an antecedent malignant hematological disease before occurrence of HL.

Introduction

Hodgkin lymphoma (HL) has an annual incidence of two to three cases per 100,000 person-years and comprises about 25% of malignant nodal lymphomas worldwide [START_REF] Parkin | Cancer incidence in five continents. Comparability and quality of data[END_REF]. In developed countries, the incidence rate has slightly decreased in the last 20 years and, based on modern systemic oncologic treatments, survival has improved markedly over time [START_REF] Cartwright | Time trends in incidence of haematological malignancies and related conditions[END_REF]. HL is characterized morphologically by the presence of distinctive neoplastic giant cells, Hodgkin and Reed-Sternberg (HRS) cells, which are embedded in a reactive cellular background [START_REF] Tzankov | Pathobiology of classical Hodgkin lymphoma[END_REF]. For a long time, the neoplastic nature of the HRS cells was highly controversial but nowadays it is clear that HL is a lymphoproliferative disease mostly of B cell nature [START_REF] Kuppers | The origin of Hodgkin and Reed/ Sternberg cells in Hodgkin's disease[END_REF]. According to the World Health Organization (WHO) classification, two biologically and clinically different entities are distinguished: nodular lymphocytic predominant HL (NLPHL, nodular paragranuloma) and classical Hodgkin lymphoma (cHL), the latter entity including nodular sclerosis (NS), mixed cellularity (MC), lymphocyte-rich and lymphocyte depletion (LD) cHL [START_REF] Jaffe | Pathology and genetics of tumors of haematopoietic and lymphoid tissues[END_REF]. cHL comprises approximately 95% of all HL cases and shows a bimodal age distribution with a major peak in young adults and a minor peak in late life. In contrast, NLPHL can occur at any age but there is a peak of incidence in the fourth decade [6]. NS is the predominant histological subtype in developed countries, whereas MC is more frequent in developing countries. Several risk factors have been described to be associated with the development of HL [START_REF] Gutensohn | Childhood social environment and Hodgkin's disease[END_REF][START_REF] Glaser | Epstein-Barr virus-associated Hodgkin's disease: epidemiologic characteristics in international data[END_REF][9][START_REF] Alexander | Community lifestyle characteristics and incidence of Hodgkin's disease in young people[END_REF]. The presence of Epstein-Barr virus (EBV) in HRS cells may be related to prognosis in some instances [START_REF] Keegan | Epstein-Barr virus as a marker of survival after Hodgkin's lymphoma: a population-based study[END_REF][START_REF] Jarrett | Impact of tumor Epstein-Barr virus status on presenting features and outcome in age-defined subgroups of patients with classic Hodgkin lymphoma: a population-based study[END_REF][START_REF] Krugmann | Longer failure-free survival interval of Epstein-Barr virus-associated classical Hodgkin's lymphoma: a single-institution study[END_REF]. EBV is a ubiquitous herpes virus of known oncogenic potential, which can be detected in the malignant HRS cells of 30% to 100% of HL patients, dependent on the geographic area [START_REF] Weiss | Epstein-Barr viral DNA in tissues of Hodgkin's disease[END_REF][START_REF] Pallesen | Expression of Epstein-Barr virus latent gene products in tumour cells of Hodgkin's disease[END_REF].

The prognosis and management of HL is dictated by disease stage and other risk factors rather than histology [START_REF] Horwitz | Advances in the treatment of Hodgkin's lymphoma[END_REF]. Depending on stage and risk factor profile, on average, more than 80% of patients with HL can be cured with effective first-line therapy [START_REF] Rosenberg | The management of Hodgkin's disease: half a century of change. The Kaplan Memorial Lecture[END_REF]. Today, doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD), often combined with involved field radiotherapy, is the most commonly applied treatment regimen and is standard treatment for patients with early-stage disease without additional risk factors [START_REF] Bonadonna | ABVD plus subtotal nodal versus involved-field radiotherapy in early-stage Hodgkin's disease: long-term results[END_REF][START_REF] Engert | Involved-field radiotherapy is equally effective and less toxic compared with extended-field radiotherapy after four cycles of chemotherapy in patients with early-stage unfavorable Hodgkin's lymphoma: results of the HD8 trial of the German Hodgkin's Lymphoma Study Group[END_REF][START_REF] Meyer | Randomized comparison of ABVD chemotherapy with a strategy that includes radiation therapy in patients with limited-stage Hodgkin's lymphoma: National Cancer Institute of Canada Clinical Trials Group and the Eastern Cooperative Oncology Group[END_REF][START_REF] Canellos | Chemotherapy of advanced Hodgkin's disease with MOPP, ABVD, or MOPP alternating with ABVD[END_REF][START_REF] Gobbi | ABVD versus modified Stanford V versus MOPPEBVCAD with optional and limited radiotherapy in intermediate-and advanced-stage Hodgkin's lymphoma: final results of a multicenter randomized trial by the Intergruppo Italiano Linfomi[END_REF]. For advanced-stage HL, the (dose-escalated) bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP) protocol has been shown to be superior to less-intensive regimens [START_REF] Diehl | Standard and increased-dose BEA-COPP chemotherapy compared with COPP-ABVD for advanced Hodgkin's disease[END_REF]. The major drawback that hampers the clinical achievements during the last decades is the increasing incidence of late toxicities and treatment complications. Of note, secondary malignancies seem to be a major cause of morbidity and mortality among long survivors of HL [START_REF] Hoppe | Hodgkin's disease: complications of therapy and excess mortality[END_REF][START_REF] Aleman | Long-term causespecific mortality of patients treated for Hodgkin's disease[END_REF].

In this population-based study, taking the advantage of the demographically well-documented population of Tyrol (http://www.tirol.gv.at/themen/zahlenundfakten/statistik), we retrospectively investigated the epidemiological and clinical characteristics of all HL patients diagnosed within the period from 1993 to 2005 and analyzed treatment outcomes, toxicities, and long-term results as well as antecedent and subsequent malignancies.

Materials and methods

Patients

The demographic and clinical data of all patients are listed in Table 1. Our study comprised 158 patients without evidence of HIV infection diagnosed with HL between 1 January, 1993 and 30 June, 2005 at the Institute of Pathology at the Medical University of Innsbruck. Inci- that were active at time of the patients' diagnosis. Disease remission was defined as absence of disease for at least 1 month as determined by laboratory and imaging studies as well as physical examination. Disease relapse was defined as disease progression occurring at least 3 months after achieving disease remission. Early relapse required a complete remission lasting ≥3 months to 12 months. Late relapse was defined as relapse after complete remission lasting >12 months. Treatment failure was defined as disease relapse or primary treatment resistance. Diseasespecific mortality was defined as patient deaths due to or with symptomatic-detectable lymphoma.

Histopathology and immunohistochemistry

All 158 tumors were reclassified on hematoxylin-and-eosin (H&E)-and Giemsa-stained slides and histological type was reassessed according to the current World Health Organization classification [START_REF] Jaffe | Pathology and genetics of tumors of haematopoietic and lymphoid tissues[END_REF]. Routinely, all cases were stained for CD15 and CD30 and in 52% of cases for LMP1 if cHL was suspected on H&E-stained slides. In addition, staining for CD20, CD45RA, CD57, and the immunoglobulin J-chain was carried out if NLPHL was suspected. Standard immunoperoxidase techniques were applied using an automated immunostaining device (Nexes®, Ventana Tucson, AZ, USA) as described previously [START_REF] Tzankov | Expression of B-cell markers in classical Hodgkin lymphoma: a tissue microarray analysis of 330 cases[END_REF].

Diaminobenzidine was used as chromogen. For negative controls, the primary antibodies were omitted.

Statistics

Current life status data of all patients, including cause of death, were available from the Cancer Registry of Tyrol. Incidence was calculated as sex-specific and age-adjusted standardized incidence rate using Segi's population weighting [START_REF] Segi | The age-adjusted death rates for malignant neoplasms in some selected sites in 23 countries in 1954-1955 and their geographical correlation[END_REF] for the Tyrolean population, which is reported annually by the Tyrolean government (http://www.tirol.gv. at/themen/zahlenundfakten/statistik). Statistical analysis was performed using the Statistical Software Package of Social Sciences 15.0, applying descriptive methods, Pearson χ 2 and Mann-Whitney U test. Time trend curves were constructed using the curve estimation option. For investigation of the annual incidence changes, a least-square regression analysis of the standardized incidence rate weighted by the absolute number of cases was applied. Survival was estimated by the Kaplan-Maier method and compared by the log-rank test. p values <0.05 were considered significant.

Results

The main characteristics of the study population are summarized in Table 1. The median age at diagnosis of cHL was 39 years (range, 10-85 years) and 36 years (range; 14-51) for NLPHL. Similar to that reported from other cancer registries, the age-adjusted incidence rate was 1.98 (1.2-2.9) per 100,000 person-years. Depending on the absence or presence of risk factors according to the GHSG, 42 (27%) patients were diagnosed with favorable disease, 41 (26%) with intermediate, and 60 (38%) with advanced disease, respectively. In 15 cases, the risk factors according to the GHSG were unknown. Fifty one (32%) of the patients were enrolled in clinical trials of the GHSG. Risk-adapted treatment given according to GHSG stratification criteria is summarized in Table 2. The 5-and 10-year overall survival (OS) rates for the patients with cHL were 89% and 85%, respectively, whereas all ten patients with NLPHL are still alive (Fig. 1). NS was, as expected, the predominant histological subtype (64%) and occurred more frequently in younger individuals, while MC cHL was more commonly seen in the elderly.

In cHL, patients' age (p<0.01), sex (p=0.03), risk groups according to the GHSG stratification (p<0.01; Fig. 2), presence of B symptoms (p<0.01), and bone marrow infiltration (p<0.01) were of prognostic significance regarding OS, whereas histological subtype, extranodal involvement (except bone marrow), and bulky disease were not. Data on the EBV status were available only for a subgroup of 77 patients (52%) and therefore not sufficient for valid subgroup analyses. Patients enrolled in clinical trials of the GHSG showed a trend towards better OS than patients being treated outside trials (Fig. 3). Notably, patients with advanced-stage HL (n=49), who received combined modality treatment according to the GHSG, had significantly better OS than those treated by chemotherapy alone (p=0.01; Fig. 4). The relapse rate in 156 patients for whom complete follow-up data were available was 13%; 11 (7%) patients (eight cHL, three NLPHL) had early and ten (6%) patients (all cHL) late relapses, respectively. Within the median observation period of 45 months (range 3-148), three of 146 patients (2%) with cHL developed a second hematological malignancy: two secondary acute myelogenous leukemias and one diffuse large B cell lymphoma. Furthermore, one female patient (0.6%) developed breast cancer. The details of all second malignancies are listed in Table 3. All four cHL patients developing a secondary neoplasia had received a combined modality treatment with cyclophosphamide, vincristine, and prednisone (COPP)-ABVD followed by radiotherapy. Second malignancies occurred on an average of 47 months (range 22-60) after diagnosis of cHL. Moreover, five patients (3%) had already experienced a malignant lymphoproliferative disease preceding cHL which occurred on an average of 97 months (range 37-175) before cHL was diagnosed (Table 3).

Concerning treatment-related toxicity, bleomycin-induced lung toxicity was observed in six (4%) patients (Table 4). Of these, five patients had received ABVD whereas only one patient had been treated according to the BEACOPP protocol. Diagnosis of bleomycin-induced pneumonitis (BIP) was based on clinical symptoms, supported by typical With respect to infectious complications, five (3%) patients developed lethal treatment-related infections (Table 4): one patient undergoing first-line treatment with BEACOPP died from a disseminated invasive mycosis (Aspergillus fumigatus); another two patients died during treatment with BEACOPP due to fatal bacterial infections. Moreover, two patients deceased because of Gramnegative sepsis after receiving salvage chemotherapy. Five (3%) patients died from progressive or recurrent disease and three (2%) due to a secondary malignancy.

Discussion

Our findings in a well-documented patient population of 158 HL that have been diagnosed among Tyrolean inhabitants during the period 1993-2005 are comparable with those reported from large randomized studies conducted by the GHSG. These results provide evidence that patients with HL in Tyrol are treated according to state-of- the-art criteria and carry an excellent long-term prognosis with 5-and 10-year OS rates for the total group of 89% and 85%, respectively. The age-adjusted incidence rate for HL has been reported to be 2.7 per 100,000 person-years [START_REF] Ries | SEER cancer statistics review, 1973-1996[END_REF].

In our study, the age-adjusted incidence rate was slightly lower with 1.98 (1.2-2.9) per 100,000 person-years confirming a previous epidemiologic analysis carried out between 1988 and 1992 [START_REF] Micheli | Cancer prevalence in European registry areas[END_REF]. Thus, the incidence of HL appears to be rather stable in Tyrol over the last 20 years, which is in keeping with data from other European countries [START_REF] Micheli | Cancer prevalence in European registry areas[END_REF][START_REF] Rodriguez-Abreu | Epidemiology of hematological malignancies[END_REF]. Nowadays, HL has become one of the most efficiently curable malignancies achieved by appropriate selection of patients for risk-adjusted therapy regimens. However, two major problems remain challenging: development of secondary malignancies as the most serious late complication of HL as well as acute toxicities, particularly myelosuppression, infectious complications, and bleomycin-associated lung toxicity. The malignancies most frequently associated with chemotherapy include acute myeloid lymphoma (AML), myelodysplastic syndromes, and non-Hodgkin lymphomas, whereas solid tumors appear more commonly after radiotherapy [START_REF] Josting | Secondary myeloid leukemia and myelodysplastic syndromes in patients treated for Hodgkin's disease: a report from the German Hodgkin's Lymphoma Study Group[END_REF][START_REF] Behringer | Solid tumors in patients treated for Hodgkin's disease: a report from the German Hodgkin Lymphoma Study Group[END_REF][START_REF] Hodgson | Long-term solid cancer risk among 5-year survivors of Hodgkin's lymphoma[END_REF][START_REF] Munker | Second malignancies after Hodgkin's disease: the Munich experience[END_REF][START_REF] Ng | Second malignancy after Hodgkin disease treated with radiation therapy with or without chemotherapy: long-term risks and risk factors[END_REF]. The absolute excess risk for secondary neoplasias in patients with HL has been reported to range between 40 and 90 malignancies per 10,000 patient years (0.4% to 0.7% per year) [START_REF] Ng | Second malignancy after Hodgkin disease treated with radiation therapy with or without chemotherapy: long-term risks and risk factors[END_REF][START_REF] Van Leeuwen | Second cancer risk following Hodgkin's disease: a 20-year follow-up study[END_REF]. In line with these data, three (2%) patients of our cohort developed secondary hematological malignancies and one patient (0.6%) developed breast cancer. All four patients had received a combined modality treatment with COPP-ABVD regimen followed by radiotherapy. Second malignancies occurred on an average of 47 months after diagnosis of HL. Moreover, five patients (3%) had a malignant hematological disease before occurrence of cHL, an issue that has only rarely been addressed before. Of these patients, two developed cHL within a mean of 91 months after diagnosis of B chronic lymphocytic leukemia (CLL). In another two patients, cHL occurred within a mean period of 139 months after diagnosis of diffuse large B cell lymphoma and in one patient cHL was diagnosed 38 months after diagnosis of follicular lymphoma. Both patients with B-CLL who developed an HL variant of Richter's syndrome had received fludarabine. In one of them, we were able to demonstrate a clonal relationship between B-CLL and microdissected HRS cells as reported previously [START_REF] Fong | Hodgkin's disease variant of Richter's syndrome in chronic lymphocytic leukaemia patients previously treated with fludarabine[END_REF]. Whether this co-occurrence of second lymphoproliferative diseases in cHL patients is coincidental or a result of patient's genetical background, making B cells prone to malignant transformation, or due to presence of malignant B stem cells, giving origin to different lymphomas, is currently unclear.

Treatment strategies of HL have changed during the recent years. Since the optimal strategy has not yet been defined, the aim of the current treatment protocols is not only to prolong disease free and OS but also to reduce toxicity. Myelosuppression is a common side effect of BEACOPP regimens and might be complicated by serious bacterial, viral, and fungal infections. Recently, acute hematologic toxicity of the HD9 study patients being treated with BEACOPP regimens has been reported by the GHSG [START_REF] Engel | Acute hematologic toxicity and practicability of dose-intensified BEA-COPP chemotherapy for advanced stage Hodgkin's disease. German Hodgkin's Lymphoma Study Group (GHSG)[END_REF]. The occurrence of WHO grade 4 leukopenia was documented in 38% (BEACOPP-baseline) and 92% (BEACOPP-escalated) of the patients. Six patients (1.4%) died from acute toxicity during BEACOPP-baseline therapy and four (0.9%) patients died receiving BEACOPPescalated, respectively. Specific data on the incidence and cause of infections during both regimens were not fully available due to incomplete documentation. In our retro- spective study, five (3%) patients died of lethal treatmentrelated infectious complications. Of these, three patients have been treated first line with BEACOPP regimen and two patients died during high-dose salvage chemotherapy for relapsed cHL. Thus, when applying these regimens, careful monitoring of acute toxicities is of paramount importance inside and outside clinical trials. Another life-threatening complication is the induction of fatal pulmonary toxicity associated with the use of bleomycin. The preferential pulmonary involvement (along with skin toxicity) in bleomycin toxicity (BIP) can be explained by lack of the bleomycin-inactivating enzyme bleomycin hydrolase in these tissues [START_REF] Dorr | Bleomycin pharmacology: mechanism of action and resistance, and clinical pharmacokinetics[END_REF]. With the use of bleomycin, various pulmonary syndromes have been described such as bronchiolitis obliterans with organizing pneumonia [START_REF] Santrach | Nodular form of bleomycin-related pulmonary injury in patients with osteogenic sarcoma[END_REF], eosinophilic hypersensitivity [42], and, most commonly, interstitial pneumonitis. This BIP has been reported in up to 46% of patients treated with bleomycincontaining chemotherapy regimens [START_REF] Van Barneveld | Predictive factors for bleomycininduced pneumonitis[END_REF][START_REF] Dearnaley | Combination chemotherapy with bleomycin, etoposide and cisplatin (BEP) for metastatic testicular teratoma: long-term follow-up[END_REF][START_REF] Jules-Elysee | Bleomycin-induced pulmonary toxicity[END_REF][START_REF] Levi | The importance of bleomycin in combination chemotherapy for good-prognosis germ cell carcinoma. Australasian Germ Cell Trial Group[END_REF][START_REF] Real | Life threatening lung toxicity induced by low doses of bleomycin in a patient with Hodgkin's disease[END_REF][START_REF] Bredenfeld | Severe pulmonary toxicity in patients with advanced-stage Hodgkin's disease treated with a modified bleomycin, doxorubicin, cyclophosphamide, vincristine, procarbazine, prednisone, and gemcitabine (BEACOPP) regimen is probably related to the combination of gemcitabine and bleomycin: a report of the German Hodgkin's Lymphoma Study Group[END_REF]. In the present study, BIP was rather infrequent with six (4%) patients, five receiving ABVD regimen and one BEACOPP, respectively. Recent reports showed a significantly increased risk of BIP in HL patients being treated with bleomycin-containing chemotherapy when granulocyte colony-stimulating factor (G-CSF) was additionally used [START_REF] Martin | Bleomycin pulmonary toxicity has a negative impact on the outcome of patients with Hodgkin's lymphoma[END_REF][START_REF] Dirix | Pulmonary toxicity and bleomycin[END_REF][START_REF] Matthews | Pulmonary toxicity of ABVD chemotherapy and G-CSF in Hodgkin's disease: possible synergy[END_REF]. As G-CSF is widely applied to avoid chemotherapy-associated treatment delays, further attention on this coincidence is warranted.

In conclusion, our retrospective study provides evidence that Tyrol patients with HL are efficiently treated according to the standard of care guidelines or within GHSG trials and have an excellent long-term prognosis. However, even modern treatment regimens leave space for improvement to minimize severe side effects, in particular, infectious complications and BIP.

Disclosure or conflict of interest

There is no duality of interest to be disclosed.

Fig. 2 Fig. 3

 23 Fig. 2 Overall survival of cHL patients, to whom the GHSG risk-group stratification could be applied. Patients with favorable and intermediate stage had a significantly better overall survival rate than patients in advanced-stage disease as assessed by log-rank test (p<0.01)

Fig. 1

 1 Fig.1Overall survival of patients with cHL and NLPHL diagnosed between 1993 and 2005 in Tyrol. The 5-and 10-year overall survival rates for the patients with cHL were 89% and 85%, respectively. All ten patients with NLPHL are still alive

Fig. 4

 4 Fig.4Overall survival of patients with advanced-stage cHL according to the GHSG stratification. Treatment with combined modality resulted in a significantly better overall survival than with chemotherapy alone (log-rank test, p=0.01)

Table 1

 1 Demographic and clinical data of patients

	Characteristics	Patient cHL	Patient NLPHL
		No	%	No	%
	Age group
	0-35	64	(44)	4	(40)
	36-55	42	(28)	6	(60)
	over 55	42	(28)
	All	148		10
	Sex
	Male	78	(53)	5	(50)
	Female	70	(47)	5	(50)
	Histology
	NS	95	(64)
	MC	44	(30)
	LP	4	(3)
	Unclassifiable	5	(3)
	Latent membrane protein1
	Yes	24	(16)
	No	53	(36)
	Unknown	71	(48)
	Stage (according to GHSG)
	Favorable	39	(26)	3	(30)
	Intermediate	39	(26)	2	(20)
	Advanced	55	(38)	5	(50)
	Unknown	15	(10)
	Presence of risk factors
	No	43	(29)	4	(40)
	Yes	87	(59)	6	(60)
	Unknown	18	(12)
	B symptoms
	No	78	(53)	8	(80)
	Yes	57	(38)	2	(20)
	Unknown	13	(9)
	Bone marrow involvement
	No	135	(92)	10	(100)
	Yes	8	(5)
	Unknown	5	(3)
	Therapy modality
	ABVD	70	(47)	5	(50)
	based + RTX
	BEACOPP	15	(10)	1	(10)
	based + RTX
	ABVD based	23	(16)	3	(30)
	BEACOPP based	13	(9)		(10)
	RTX alone	4	(3)
	Other	3	(2)
	Unknown	20	(13)	1
	Treatment
	Outside trial	99	(67)	8	(80)
	In trial	49	(33)	2	(20)
	Relapse
	No	128	(87)	7	(70)
	Early	8	(5)	3	(30)
	Late	10	(7)
	Unknown	2	(1)

the modified version of the Ann Arbor classification that supplements additional information on the absence or presence of the following risk factors

[START_REF] Diehl | Early, intermediate and advanced Hodgkin's lymphoma: modern treatment strategies[END_REF]

: (1) three or more involved areas, (2) large mediastinal mass (≥1/3 of thoracic diameter), (3) extranodal disease extension, and (4) elevated erythrocyte sedimentation rate (≥50 mm/h without or ≥30 mm/h with B symptoms). Bulky disease was defined as a nodal tumor mass >5 cm. Patients received either standard treatment or therapy according to investigational protocols of the German Hodgkin Study Group (GHSG)

Table 2

 2 Treatment of HL variants according to GHSG stages

		cHL (n)	NLPHL (n)
	Treatment of favorable stages
	IF-RT	2
	ABVD + RT	24	3
	ABVD	8
	Treatment of intermediate stages
	ABVD + RT	28	1
	ABVD	4
	BEACOPP + RT	6	1
	BEACOPP	1
	Treatment of advanced stages
	ABVD + RT	14	1
	ABVD	10	3
	BEACOPP + RT	9
	BEACOPP	12
	Other	3
	Unknown	27	1

Table 3

 3 Second malignancies

	Patient		Disease		Therapy	HL
	Sex	Age, years	Diagnosis	Type		Diagnosis	Subtype	Stage	EBV	Modality
		(diagnosis	(month/			(month/			association
		HL)	year)			year)
	Second malignancy before HL
	M	71	05/1990	Squamous cell	Surgery; RTX	07/1993	MC	IA	n.d.	Combined
				carcinoma
	M	68	11/1997	CLL	COP; Fludarabine;	05/2004	MC	IIB	LMP +	Radiotherapy
					INF-α; Gupta et al;
					Rituximab
	F	81	07/1994	CLL	COP; CHOP;	02/2003	MC	IB	LMP +	Radiotherapy
					Fludarabine;
					Alemtuzumab
	M	72	03/1983	DLBCL	Semicastration;	11/1997	MC	IIA	LMP +	Combined
				of testis	4× CHOP
	F	58	07/1993	DLBCL	6× CEOP-/IMVP16-	12/2001	MC	IIA	n.d.	Combined
					Dexa
	F	61	01/1996	FL	6× CHOP; IFN-	02/1999	MC	IIA	LMP-	Combined
					α; RTX
	Second malignancy after HL
	M	50	05/2000	AML	Cytarabine,	06/1995	NS	IIA	n.d.	Combined
					idarubicin
	F	61	02/2004	AML	Sibling-PBSCT;	02/1999	MC	IIA	LMP-	Combined
					FLAG
	F	67	01/1998	DLBCL	6× CHOP;	04/1996	MC	IIIA	n.d.	Combined
					3× IMVP16; RTX
	F	27	01/1999	Breast cancer	6× Epirubicin/Taxol;	03/1995	NS	I B	LMP-	Combined
					mastectomy

Table 4

 4 Treatment related toxicity

	Safety
	Patient		Stage HL	Planned treatment	Treatment given
	Sex	Age, years (diagnosis HL)
	Bleomycin-induced pneumonitis
	M	72	III A	8× ABVD	6× ABVD
	F	77	IIA	4× ABVD	2× ABVD
	M	72	IA	4× ABVD + IF-RTX	3× ABVD + IF-RTX
	M	68	IIIA	8× ABVD	2× ABVD + 4× COPP
	M	59	IIA	4× ABVD + IF-RTX	3.5× ABVD + IF-RTX
	F	39	IIIA	8× BEACOPPesc + IF-RTX	4× BEACOPPesc IF-RTX
	Lethal infectious complications
	F	36	IIIB	MUD-PBSCT	Bacterial infection
	M	61	IIIB	BEACOPPbas	Bacterial infection
	F	50	IVB	BEACOPPesc	Bacterial infection
	M	51	IIIB	DHAP	Bacterial infection
	M	39	IIB	BEACOPPesc	Invasive mycosis


Dietmar Jörg Dinter
email: dietmar.dinter@medma.uni-heidelberg.de

Wolfgang K Neff

Johanna Klaus

Christoph Böhm

Jan Hastka

Christel Weiss

Stefan O Schoenberg

Georgia Metzgeroth

Comparison of whole-body MR imaging and conventional X-ray

Keywords: Multiple myeloma, Magnetic resonance imaging, X-ray skeletal survey, Whole-body imaging, Salmon and Durie

Introduction

Multiple myeloma, a malignant monoclonal plasma cell disease, is the most common tumor of the bone marrow; nevertheless, the incidence of this tumor is only four in 100,000 per year. However, the diagnosis has great implications in the clinical setting because of the long-term prognosis for these patients, extending over decades [START_REF] Kelly | Neuropathies of monoclonal gammopathies of undetermined significance[END_REF]. According to the Salmon and Durie classification, no relevant decrease in life span is seen in patients with stage I myeloma. In stage II and even more so in stage III disease, however, a significant decrease in life expectancy is observed, where only 20% of patients survive more than 2 years if they do not receive appropriate treatment [START_REF] Baur | Magnetic resonance imaging as a supplement for the clinical staging system of Durie und Salmon?[END_REF]. Therefore, efficient staging is crucial in multiple myeloma because of the implications for initiating adequate therapy [START_REF] Durie | The role of anatomic and functional staging in myeloma: description of Durie/Salmon plus staging system[END_REF]. The therapeutic strategies consist of various chemo-therapy regimens and stem cell transplantation as an additional therapeutic option that increases the clinical response and life expectancy [START_REF] Durie | Scientific Advisors of the International Myeloma Foundation (2003) Myeloma management guidelines, a consensus report from the Scientific Advisors of International Myeloma Foundation[END_REF].

A worldwide accepted staging system has been established by Durie and Salmon [START_REF] Durie | A clinical staging system for multiple myeloma. Correlation of measured myeloma cell mass with presenting clinical features, response to treatment, and survival[END_REF], who demonstrated a significant correlation between the clinical and laboratory findings and tumor load with life expectancy. Due to the limitations of this staging system, mainly related to false-negative findings in conventional X-ray examination in the initial stages of the disease, some authors suggested implementing magnetic resonance imaging (MRI) into the staging system [START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF]. This so-called Durie and Salmon PLUS staging system introduced stage IA, either no lesion or a solitary lesion on MRI; stage IB, less than five lesions or mild diffuse infiltration; stage IIA/B, five and up to 20 focal lesions or moderate diffuse infiltration; and stage IIIA/B, more than 20 focal lesions or extensive diffuse infiltration [START_REF] Durie | The role of anatomic and functional staging in myeloma: description of Durie/Salmon plus staging system[END_REF][START_REF] Durie | Scientific Advisors of the International Myeloma Foundation (2003) Myeloma management guidelines, a consensus report from the Scientific Advisors of International Myeloma Foundation[END_REF][START_REF] Baur-Melnyk | Role of MRI for the diagnosis and prognosis of multiple myeloma[END_REF].

Therefore, MRI is playing an increasing role in the diagnosis of multiple myeloma [START_REF] Eustace | A comparison of whole body turbo STIR MR imaging and planar 99Tc-methylene diphosphonate scintigraphy in the examination of patients with suspected skeletal metastases[END_REF]. Various authors have demonstrated the high sensitivity of MRI in detecting plasma cell infiltrations [START_REF] Baur | Magnetic resonance imaging as a supplement for the clinical staging system of Durie und Salmon?[END_REF][START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF][START_REF] Baur-Melnyk | Role of MRI for the diagnosis and prognosis of multiple myeloma[END_REF][START_REF] Lecouvet | Stage III multiple myeloma: clinical and prognostic value of spinal bone marrow MR imaging[END_REF][START_REF] Lecouvet | Vertebral compression fractures in multiple myeloma. Part II. Assessment of fracture risk with MR imaging of spinal bone marrow[END_REF][START_REF] Mariette | Prognostic value of vertebral lesions detected by magnetic resonance imaging in patients with stage I multiple myeloma[END_REF][START_REF] Steinborn | Whole-body bone marrow MRI in patients with metastatic disease to the skeletal system[END_REF]. In contrast to conventional skeletal X-ray surveys (X-ray survey), MRI can precisely evaluate the bone marrow. The pathomorphological features of the plasma cell clusters such as increased cellular density, loss of the fatty bone marrow components, and neovascularization of tumor cells can be visualized and more accurately differentiated [START_REF] Baur | Neovascularization of bone marrow in patients with diffuse multiple myeloma: a correlative study of magnetic resonance imaging and histologic findings[END_REF].

As a result of technical improvements that have enabled the clinical use of a whole-body MRI protocol (wb-MRI), patient examinations are completed within 40 min. By implementing new coil concepts for whole-body imaging with stepwise table movement and in conjunction with parallel acquisition techniques, wb-MRI can now be employed in clinical routine [START_REF] Lecouvet | Skeletal survey in advanced multiple myeloma: radiography versus MRI survey[END_REF]. This new technique has been established as a reliable method for the diagnosis of bone metastases, solid tumors, and lymphomas [START_REF] Eustace | A comparison of whole body turbo STIR MR imaging and planar 99Tc-methylene diphosphonate scintigraphy in the examination of patients with suspected skeletal metastases[END_REF][START_REF] Ghanem | Comparative diagnostic value and therapeutic relevance of magnetic resonance imaging and bone marrow scintigraphy in patients with metastatic solid tumor of axial skeleton[END_REF][START_REF] Ghanem | Diagnostic value of MRI in comparison to scintigraphy, PET, MS-CT and PET/CT for the detection of metastases of bone[END_REF][START_REF] Schäfer | Oncologic screening with whole-body MRI: possibilities and limitations[END_REF]; however, the sensitivity of wb-MRI for detecting bone marrow infiltration has not yet been evaluated extensively [START_REF] Ghanem | Whole-body MRI in the detection of bone marrow infiltration in patients with plasma cell neoplasms in comparison to radiologic skeletal survey[END_REF].

The aim of this study, therefore, was to compare the sensitivity of wb-MRI with that of X-ray survey in detecting myeloma clusters in the bone by classifying the different patterns of infiltration. Furthermore, the impact of wb-MRI on staging patients according to Durie and Salmon PLUS versus the classic Durie and Salmon scheme was analyzed. Finally, the influence of wb-MRI on changing therapy was evaluated.

Material and methods

Patients

Sixty patients with clinically proven multiple myeloma in different stages (Table 1) were prospectively evaluated with wb-MRI between January 2005 and January 2007. The sample size calculation was based on the examples of eight sections and provided about 60 cases for each region.

Conventional X-ray skeletal survey of the entire axial skeleton was performed within 12.3±3.5 days. The patient age range was 37-93 years (mean 65.1±11.7 years). The institutional review board and the local ethics committee approved the protocol and the study was performed according to the guidelines of Helsinki. Written informed consent was obtained from all patients.

Clinical data

The clinical data of the patients were evaluated retrospectively by using the patient charts. The maximum interval between assessment of the clinical data and the wb-MRI examination was ±2 weeks. The date of first diagnosis, initial stage, type of multiple myeloma, and laboratory findings (serum and urine protein, electrophoresis, hemoglobin levels, 24-h urinary protein excretion, serum β 2microglobulin, and results of electrophoresis) were recorded for all patients. In addition, the results of bone marrow aspiration were available for 40 of the 60 patients. Patients with a secondary malignoma were excluded from the study. Imaging X-ray survey of the entire axial skeleton was performed using a standard X-ray unit (Multix Top, Siemens Medical Solutions, Erlangen, Germany) and standard imaging parameters for each skeletal region. Radiographs were available for the diagnostic regions of interest, which included the skull and spine in two planes and thorax, pelvis, arm and forearm, and upper and lower leg in one plane each.

wb-MRI was performed using a 1.5-T magnetic resonance system with matrix coils, 18 independent receiver channels, and a 205-cm range of table movement for whole-body imaging (Magnetom Avanto, Siemens Medical Solutions, Erlangen, Germany). The examination protocol consisted of coronal T1-and T2-STIR-weighted images at four table positions. Furthermore, sagittal T1-and T2- STIR-weighted images of the spine were acquired (Table 2). The entire examination protocol took 37 min 23 s, with a maximum room time of between 45 and 50 min.

Image analysis

For comparison of wb-MRI with the X-ray survey, the body was divided into eight different segments: skull, spine, thorax, right and left upper extremity, pelvis, and right and left lower extremity. A total of 60 MRI examinations with 480 segments were available for comparative analysis. For both the X-ray survey and the wb-MRI examinations, the written reports were used as the primary source for analyzing the findings. An experienced radiologist blinded to the results of the initial reports analyzed the results a second time. For discrepant findings, a final consensus analysis together with another blinded radiologist with more than 8 years of experience in reading musculoskeletal MRI was carried out. To account for the different types of bone marrow involvement by multiple myeloma, different MRI patterns of infiltration were defined: normal finding, focal infiltration, multifocal infiltration (>ten focal lesions), diffuse infiltration, and mixed focal-diffuse infiltration, as described by Baur-Melnyk et al. [START_REF] Baur-Melnyk | Role of MRI for the diagnosis and prognosis of multiple myeloma[END_REF]. In the X-ray survey, patterns of infiltration were described according to the Durie and Salmon classification [START_REF] Durie | A clinical staging system for multiple myeloma. Correlation of measured myeloma cell mass with presenting clinical features, response to treatment, and survival[END_REF]: normal or solitary lesion (stage I), multiple osteolysis or generalized striated osteoporosis (stage III), and stage II (neither I nor III). To assess the effect of wb-MRI on staging, all patients were categorized after acquiring all relevant clinical data according to the standard classification of Durie and Salmon and also according to Durie and Salmon PLUS with regard to the wb-MRI findings. Thereby, the two different clinical staging systems could be directly compared based on the individual scores for the tumor stage.

Using a modified Likert-type scale, the degree of influence of wb-MRI on further treatment was assessed by two board-certified oncologists with more than 3 years of special training in hematooncology. This assessment also included the pathologic laboratory ranges and X-ray survey findings. Pathologic laboratory parameters were defined as follows: (1) paraprotein IgG>5 g/dl, IgA>3 g/dl; (2) hemoglobin <10 g/dl; and (3) elevated serum calcium levels. The Likert-type scale had three ranges, with increasing influence of wb-MRI on the therapeutic decision:

-Grade I: wb-MRI did not influence therapy because three or four other parameters (paraprotein, hemoglobin, X-ray survey, or serum calcium levels) already indicated the need for a specific therapy. -Grade II: wb-MRI had a minor influence on therapy because one or two other parameters as mentioned above were abnormal, indicating the need for further treatment.

-Grade III: wb-MRI was essential for initiation of therapy without further parameters influencing the therapeutic decision.

Statistical methods

For statistical analysis, the symmetry test by Bowker [START_REF] Bowker | A test for symmetry in contingency tables[END_REF] was applied. This test examines whether the matrix for the frequency of wb-MRI and X-ray survey findings is symmetric or not. A p value of less than 0.05 indicated that the matrix is not symmetrical with respect to the main diagonal. Because of the differences in the types of

Results

Comparison of wb-MRI and conventional X-ray

Concordance between X-ray survey and wb-MRI was present in 293/480 regions (61%); in four cases (0.8%), a focal infiltration was detected by X-ray survey alone without being identified by wb-MRI. However, in 183/ 480 regions (38%), wb-MRI revealed additional findings formerly not diagnosed by means of conventional X-ray examination. In 60 of these 183 regions (33%), wb-MRI provided more detailed information about the degree of infiltration. As demonstrated in Table 3, in 13 of these regions, a multifocal infiltration could be shown; in 14 regions, a diffuse infiltration was demonstrated, and, in 33 of the regions, a combination of multifocal lesions and diffuse infiltration could be found that had not been diagnosed previously by conventional X-ray examination.

In 123 of the 183 regions (67%), wb-MRI was able to diagnose infiltration in the bones that had not been detected by conventional X-ray alone. In particular, as shown in Table 3, the bone tissue had been normal in these regions on the X-ray survey. Using wb-MRI, 35 regions had additional focal lesions, 17 regions newly diagnosed multifocal lesions, 57 regions a diffuse infiltration formerly described as normal, and 14 regions multifocal lesions in combination with a diffuse infiltration pattern. Symmetry testing according to the Bowker method (weighted and unweighted) led to p values <0.0001. Table 3 demonstrates the significant asymmetry in the pattern of infiltration in favor of wb-MRI. The most common reason for discordance between the two modalities was a diffuse infiltration on wb-MRI with a normal finding on X-ray survey. Diffuse infiltration was found by X-ray survey in 23 regions, by wb-MRI in 91 regions (discordance of 75%). In 84%, a diffuse infiltration with multifocal lesions could not be detected by the X-ray survey (nine vs. 56 regions).

Comparing the different regions according to the pattern of infiltration as detected by both methods, a statistically significant difference was seen in favor of wb-MRI in the thorax, spine, pelvis, and the lower extremities on both sides (Table 4). The most important difference was found in the spine: Here, a concordance in the findings was only observed in 24/60 patients. In 24/36 patients, the conventional X-ray gave false-negative results without demonstrating any pathologic findings, and, in 12/36 patients, more detailed information about the pattern of infiltration was found. In particular, diffuse infiltration of the spine was found in only two of 60 patients, whereas wb-MRI revealed this in 15/60 patients, In the regions spine, thorax, pelvis, head, and right upper and left lower extremity, conventional X-ray did not provide any further information about infiltration of the bone. Figures 1 and2 demonstrate examples for the comparison.

Influence of wb-MRI on the staging

The results for the modified staging according to Durie and Salmon PLUS including the findings of wb-MRI are shown in Table 1. As a result of this, the tumor stage was upgraded in 41 of the 60 patients by additionally considering the wb-MRI findings.

Influence of wb-MRI on therapy management

In 36 of the 60 patients, no further therapy was required according to a summary of the different laboratory findings, X-ray survey, and wb-MRI, with respect to the previously described Likert-type grading system. In 24 patients, the intention to treat was proposed after consideration of all parameters. The degree of influence of wb-MRI on the therapeutic decision is demonstrated in Table 5. In ten of the 24 newly treated patients (42%), wb-MRI was the most important diagnostic method for deciding on further therapy.

In four of ten patients for whom wb-MRI was crucial for deciding on treatment, the examination demonstrated a pattern of infiltration that could not be detected by X-ray survey or by laboratory findings. These patients were graded as stage III after Durie and Salmon PLUS, which resulted in further therapy. In six of ten patients, an extramedullary localization could be detected; three of six patients were additionally endangered by an impending fracture. Furthermore, in one of the 60 patients who suffered from an asecretory myeloma, wb-MRI examination was the only modality that confirmed the diffuse infiltration pattern in the spine as there were no changes in laboratory values. In the remaining 14/24 patients presenting with an immediate need to treat, the clinical data were considered more important for the treatment decision than wb-MRI. In these patients, highly pathologic clinical parameters were found, for example, massive elevated paraprotein (five of 14 patients), massive anemia (three of 14 patients), increase in β 2 -microglobulin (three of 14 patients), or a combination of the different clinical parameters (three of 14 patients).

Discussion

In the present study, the clinical value of wb-MRI in patients with multiple myeloma was systematically evaluated in terms of diagnostic accuracy, impact on tumor staging, and influence on therapeutic management. This was achieved by comparing this modality to conventional X-ray skeletal survey in detecting focal and diffuse infiltration, by evaluating the Durie and Salmon PLUS versus the standard staging system, and by ranking the influence of wb-MRI against established laboratory and clinical findings.

In the past few years, wb-MRI has become an established tool in the diagnostic workup for lymphomas, bone metastasis, and also multiple myeloma [START_REF] Baur | Magnetic resonance imaging as a supplement for the clinical staging system of Durie und Salmon?[END_REF][START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF][START_REF] Baur-Melnyk | Role of MRI for the diagnosis and prognosis of multiple myeloma[END_REF][START_REF] Lecouvet | Skeletal survey in advanced multiple myeloma: radiography versus MRI survey[END_REF][START_REF] Ghanem | Whole-body MRI in the detection of bone marrow infiltration in patients with plasma cell neoplasms in comparison to radiologic skeletal survey[END_REF][START_REF] Ludwig | Magnetic resonance imaging of the spine in multiple myeloma[END_REF][START_REF] Frühwald | MRI of the lower vertebral column in patients with multiple myeloma[END_REF]. With wb-MRI, the pathomorphological features of the bone marrow such as increased cellular density, neovascularization, and a decreased fat signal in the spongious structures due to the myeloma infiltration could be detected to give a direct and exact assessment of the bone marrow [START_REF] Baur | Neovascularization of bone marrow in patients with diffuse multiple myeloma: a correlative study of magnetic resonance imaging and histologic findings[END_REF][START_REF] Vacca | Bone marrow angiogenesis in patients with active multiple myeloma[END_REF]. Especially in early stages of the disease, infiltration can be detected by wb-MRI, while the X-ray survey does not reveal any osteolysis or osteopenia [START_REF] Baur | Magnetic resonance imaging as a supplement for the clinical staging system of Durie und Salmon?[END_REF][START_REF] Berg | Stage I multiple myeloma: value of MRI in the bone marrow in the determination of prognosis[END_REF][START_REF] Berg | Nonmyelomatous monoclonal gammopathy: correlation of bone marrow MR images with laboratory findings and spontaneous clinical outcome[END_REF][START_REF] Moulopoulos | Prognostic significance of magnetic resonance imaging in patients with asymptomatic multiple myeloma[END_REF], however, because a minimum loss of 30% of spongious structures is needed to detect this [START_REF] Walker | Magnetic resonance imaging in multiple myeloma: diagnostic and clinical implications[END_REF]. Using other methods such as positron emission tomography, even with 18 F-fluoro-2-deoxyglucose, spatial resolution is too low and tracer uptake is too inconsistent in multiple myeloma to make a clinically acceptable diagnostic assessment [START_REF] Antoch | Whole-body tumor staging: MRI or FDG-PET/CT?[END_REF]. According to Baur et al. [START_REF] Baur | Magnetic resonance tomography in plasmacytoma: ranking of various sequences in diffuse and focal infiltration patterns[END_REF], wb-MRI in combination with clinical staging according to Durie and Salmon can be considered the new gold standard for the detection of focal myeloma.

In the present study, the advantage of wb-MRI over Xray survey could be confirmed: 21% of the focal and multifocal myeloma lesions, 75% of the diffuse, and 84% of the focal-diffuse infiltration could only be detected by wb-MRI. Age at presentation, diagnostic methods, time interval between X-ray and wb-MRI, and exclusion criteria were comparable to those used in studies previously published in the literature [START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF][START_REF] Lecouvet | Skeletal survey in advanced multiple myeloma: radiography versus MRI survey[END_REF][START_REF] Ghanem | Whole-body MRI in the detection of bone marrow infiltration in patients with plasma cell neoplasms in comparison to radiologic skeletal survey[END_REF].

The kind and pattern of infiltration detected on wb-MRI correlate significantly with the stage according to Durie and Salmon and therefore define the prognosis for these patients [START_REF] Durie | A clinical staging system for multiple myeloma. Correlation of measured myeloma cell mass with presenting clinical features, response to treatment, and survival[END_REF][START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF]. In addition to focal infiltration, multiple myeloma can also present with diffuse and focal-diffuse infiltration, which are significantly associated with a higher disease stage [START_REF] Lecouvet | Vertebral compression fractures in multiple myeloma. Part II. Assessment of fracture risk with MR imaging of spinal bone marrow[END_REF][START_REF] Moulopoulos | Magnetic resonance imaging of bone marrow in haematologic malignancies[END_REF]. This is either not detected by X-ray survey or is seen as sparse osteoporosis, which is difficult to distinguish from physiologically or medication-induced osteoporosis. In these patients, wb-MRI is a more sensitive technique [START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF][START_REF] Baur-Melnyk | Staging of multiple myeloma with MRI: comparison to MSCT and conventional radiography[END_REF], which has been confirmed by the present study where diffuse infiltration was not visualized in 75% and focal-diffuse infiltration in 84% of the patients on Xray survey. In line with other studies in the literature, the examinations were performed with T2-weighted STIR sequences, as first described by Rahmouni et al. [START_REF] Rahmouni | Detection of multiple myeloma involving the spine: efficacy of fat-suppression and contrast-enhanced MR-imaging[END_REF], and with T1-weighted sequences [START_REF] Lecouvet | Stage III multiple myeloma: clinical and prognostic value of spinal bone marrow MR imaging[END_REF], which have a high [START_REF] Rahmouni | Detection of multiple myeloma involving the spine: efficacy of fat-suppression and contrast-enhanced MR-imaging[END_REF][START_REF] Wasser | Correlation of MRI and histopathology of bone marrow in patients with multiple myeloma[END_REF] who demonstrated that the administration of contrast media does not provide valuable additional information for diagnosis. One limitation of biopsy is the proof of the lesionswhether they are infiltrated or not-as demonstrated by Buss et al. [START_REF] Buss | Initial bone marrow findings in multiple myeloma. Significance of plasma cell nodules[END_REF] who reported false-negative results in 26% of the biopsy specimens. In some studies, it could be shown that a diffuse pattern of infiltration as seen on the skeletal survey correlates significantly with the histologic findings. Regarding focal lesions, no significant correlation could be detected between MRI and histology. One limitation of these studies is that different regions of the body are being compared, the biopsy of the iliac crest with MRI of the spine [START_REF] Baur | Infiltration patterns of plasmacytomas in magnetic resonance tomography[END_REF][START_REF] Schmidt | Estimation of diffuse bone marrow infiltration of the spine in multiple myeloma: correlation of MRT with histological results[END_REF]. This limitation has been successfully eliminated in the present study by implementing a wb-MRI protocol with T1-and T2-STIR-weighted sequences integrating the area of biopsy.

Accurate staging of patients with multiple myeloma is highly important since it determines adequate therapy and thus prognosis. Referring to Baur et al. [START_REF] Baur | Magnetic resonance imaging as a supplement for the clinical staging system of Durie und Salmon?[END_REF][START_REF] Baur-Melnyk | Staging of multiple myeloma with MRI: comparison to MSCT and conventional radiography[END_REF], the staging system according to Durie and Salmon was modified by adding MRI of the spine to improve the prognostic impact of the different stages and to refine therapy. Vande Berg et al. [START_REF] Berg | Stage I multiple myeloma: value of MRI in the bone marrow in the determination of prognosis[END_REF] compared conventional X-ray imaging in patients with multiple myeloma stage I after Durie and Salmon with corresponding MRI of the spine, pelvis, and proximal femurs. The authors found that in 29% of the patients focal lesions could be demonstrated by MRI without there being a correlation on X-ray. A further study of the same group [START_REF] Berg | Nonmyelomatous monoclonal gammopathy: correlation of bone marrow MR images with laboratory findings and spontaneous clinical outcome[END_REF] that aimed to compare the different diagnostic methods in patients with monoclonal gammopathy of undetermined significance (n=37) concluded that focal myeloma lesions could be found on MRI in 19% of the patients. A further examination by Mariette et al. [START_REF] Mariette | Prognostic value of vertebral lesions detected by magnetic resonance imaging in patients with stage I multiple myeloma[END_REF] demonstrated, in five of 17 patients (31%) with asymptomatic multiple myeloma, focal or even diffuse infiltration already in stage I disease. In all these studies, pathologic findings were found on MRI scans in approximately 30% of the patients, resulting in a classification as advanced stage, which implies immediate initiation of chemotherapy. The results of the aforementioned studies are in agreement with the present findings, in which 19 of the 60 patients were classified in a higher stage after wb-MRI. Four of these patients were shifted from stage I to stage II (n=1) or to stage III (n=3). According to the literature, these patients benefit from the immediate initiation of chemotherapy [START_REF] Berg | Stage I multiple myeloma: value of MRI in the bone marrow in the determination of prognosis[END_REF]. In an additional 15/60 patients, stage II was upgraded to stage III on the basis of wb-MRI. So far, only few studies have demonstrated that MRI is an adequate method for follow-up of patients with multiple myeloma since changes in the signal intensity and the morphology of the lesions are seen during therapy and these changes correlate with the clinical parameters [START_REF] Rahmouni | MR appearance of multiple myeloma of the spine before and after treatment[END_REF]. Up to now, however, no publication has evaluated the influence of MRI using a whole-body approach on the decision to initiate further specific therapy. In the present study, both wb-MRI and the other parameters for staging influenced the treatment decision to various degrees. But-as described in the "Results" section-wb-MRI was primarily responsible for starting a new therapy in ten of 24 patients and had a moderate influence in another four of 24 patients.

One study limitation is that most patients had initially already been treated with conventional chemotherapy (e.g., melphalan in combination with prednisolone) or high-dose chemotherapy with stem cell transplantation. However, the aim of this study was to evaluate the influence of wb-MRI on a further therapeutic strategy with a new chemotherapy regimen. Another limitation is the problem of defining objective criteria for evaluating the influence of MRI on the initiation of a new therapy. Involving two independent and experienced hematooncologists into this study who ranked the influence of the different parameters in consensus solved this problem.

In conclusion, in the present study, we demonstrated that wb-MRI is more sensitive than conventional X-ray and can detect both focal and diffuse patterns of infiltration with a high certainty. Furthermore, wb-MRI can strongly influence the therapeutic decision in patients with multiple myeloma.

Fig. 1 a

 1 Fig. 1 a T1-weighted sagittal image of the spine, b lateral views of thoracic and lumbar spine X-ray. The T1-weighted image demonstrates complete hypointensity of the bone marrow of the spine, corresponding to a diffuse pattern of infiltration. The lateral views of

Fig. 2 a

 2 Fig. 2 a T1 and b T2-STIR-weighted coronal wb-MR image demonstrating the change in the bone marrow of the proximal femur. c X-ray of the pelvis and of the proximal femur does not show pathologic changes, thus leading to a stage I disease in X-ray andbecause of further intramedullary lesions and a diffuse infiltration of the spine-stage III in wb-MRI

Table 1

 1 Patient grading by the different staging systems

	Stage	Durie and Salmon (n)	Durie and Salmon PLUS (n)
	I	1 6	1 2
	II	21	6
	III	23	42

Table 2

 2 Examination protocol of the whole-body MRI weighted scale was defined with different values for the discrepant findings between normal, focal, multifocal, diffuse, und focal-diffuse. For further evaluation, the weighted symmetry test was performed, thus providing more reliable results. All statistical calculations were done using SAS software (release 8.02; SAS Institute Inc., Cary, NC, USA).

	Sequence	T1 SE	T2	T1 SE	T2	T1 SE	T2 STIR	T1 SE	T2	T1 SE	T2	T1 SE	T2
			STIR		STIR				STIR		STIR		STIR
	Region	Total	Total	Head-	Head-	Thorax-	Thorax-	Pelvis	Pelvis	Femur	Femur	Lower	Lower
		spine	spine	neck	neck	abdomen	abdomen					leg	leg
	TR/TE	628/12 3,770/	628/12	6,260/	579/11	5,500/	579/11	6,260/	450/11	6,260/	450/11	6,260/
			83		121		121		121		121		121
	Matrix	512×	448×	384×	512×	384×	512×	384×	512×	384×	512×	384×	512×
		90%	90%	80%	50%	80%	50%	80%	50%	80%	50%	80%	50%
	FoV	440	440	500	500	500	500	500	500	500	500	500	500
	Resolution	1×	1.1×	1.6×	2×1×	1.6×	2×1×6	1.6×	2×1×	1.6×	2×1×	1.6×	2×1×
	(mm 3 )	0.9×4	1×4	1,3×6	6	1.3×6		1.3×6	6	1.3×6	6	1.3×6	6
	TA (min,	2.34	2.45	3.12	3.2	2.58	4.1	2.58	3.2	2.43	3.2	2.43	3.2
	s)

TR repetition time, TE echo time, FoV field of view, TA acquisition time, T1 SE T1-weighted spin echo sequence, T2 STIR T2-weighted short Tau inversion recovery sequence infiltration, a

Table 3

 3 Pattern of infiltration on X-ray survey and wb-MRI

	X-ray survey
	Wb-MRI	a	b	c	d	e	Total
	a	182	4	0	0	0	186
	b	3 5	3 6	0	0	0	7 1
	c	1 7	1 3	4 6	0	0	7 6
	d	5 7	8	6	2 0	0	9 1
	e	1 4	2 5	5	3	9	5 6
	Total	305	86	57	23	9	480

a normal, b focal lesions, c multifocal lesions, d diffuse infiltration, e multifocal lesions and diffuse infiltration

Table 4 p

 4 values of the comparison between the modalities resulting from the Bowker test and the Bowker test with weighted counts .e. right upper extremity, l.u.e. left upper extremity, r.l.e. right lower extremity, l.l.e. left lower extremity, p level of significance

		Head	Thorax	Spine	r.u.e.	l.u.e.	Pelvis	r.l.e.	l.l.e.
	Bowker	0.725	0.021	<0.0001	0.151	0.099	<0.001	0.003	0.002
	Weighted Bowker	0.87	0.091	0.001	0.346	0.278	0.008	0.016	0.016
	r.u

Table 5

 5 Influence of wb-MRI on the treatment decision by laboratory findings and conventional X-ray according to the three-range Likerttype scale

	Degree of influence	Number of patients	Percentage
	1	11/24	46
	2	3/24	12
	3	10/24	42