C Leroux

S Dromain

Th Leboulleux

M De Baere

Emmanuel Ducreux

Baudin

Dr Dominique Elias
email: elias@igr.fr

D Goéré

G Leroux

C Dromain

S Leboulleux

Th De Baere

M Ducreux

E Baudin

Baere Th

Ducreux

Combined liver surgery and RFA for patients with gastroenteropancreatic endocrine tumors presenting with more than 15 metastases to the liver

Keywords: Endocrine tumor, liver metastases, hepatectomy, radiofrequency ablation

Combined liver surgery and RFA for patients with gastroenteropancreatic endocrine tumors presenting

with more than 15 metastases to the liver.

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exhibiting positive immunohistochemical staining for secretory granule or secretory vesicle markers. This simple definition distinguishes a subgroup of rare tumors characterized by common features including hormone secretions, association as part of inherited syndromes, hypervascularized stroma, and the expression of multiple peptide receptors. From a prognostic standpoint, GEPEC are characterized by a variable course among patients including the subgroup with indolent progression.

Finally, a high prevalence of hepatic metastases (LM) and their major impact on survival has made the liver a major target for therapy in well-differentiated endocrine carcinoma [START_REF] Baudin | Gastroenteropancreatic endocrine tumors: clinical characterization before therapy. A review[END_REF].

All the guidelines for the management of neuroendocrine tumors recommend the removal of LM, when possible and resection of at least 90% of the disease (19)[START_REF] Weidenmann | Consensus conference. Preoperative diagnosis and surgical management of neuroendocrine gastroenteropancreatic tumors[END_REF][START_REF] Cadiot | French guidelines for digestive cancers. Digestive endocrine tumors[END_REF] and liver surgery is considered a major tool in the therapeutic arsenal against GEPEC. A reason to support this approach is that liver surgery is potentially capable of achieving a complete response of LM which cannot be otherwise obtained. Indeed, several studies have reported 5-year survival exceeding 70% and improved survival in the subgroup of patients with LM amenable to resection [START_REF] Que | Hepatic resection for metastatic neuroendocrine carcinomas[END_REF][START_REF] Chen | Isolated liver metastases from neuroendocrine tumors : does resection prolong survival ?[END_REF][START_REF] Chamberlain | Hepatic neuroendocrine metastases : does intervention alter outcomes[END_REF][START_REF] Yao | Indications and results of liver resection and hepatic chemoembolization for metastatic gastrointestinal neuroendocrine tumors[END_REF][START_REF] Sarmiento | Surgical treatment of neuroendocrine metastases to the liver: a plea for resection to increase survival[END_REF][START_REF] Elias | Liver resection (and associated extrahepatic resections) for metastatic well-differenciated endocrine tumors: a 15year single center prospective study[END_REF]. However, the lack of randomized studies precludes any definite conclusions. There are two limitations of this approach which merit discussion. Firstly, it applies to a limited number of patients who, most of the time, have a small number of LM, and secondly, 75% of these patients relapse at 10 years (2-7). Recent progress achieved in the prognostic classification of GEPEC as well as in imaging studies has enabled a better definition of the different patient subgroups. From a prognostic point of view, we recently highlighted the major role of the number of LM and the natural tumor burden slope [START_REF] Malka | Prognostic factors of metastatic welldifferenciated gastroenteropancreatic endocrine tumors[END_REF]. We also emphasized the sensitivity of liver MRI in detecting tiny LM [START_REF] Dromain | MR imaging of hepatic metastases caused by neuroendocrine tumors : comparing four techniques[END_REF]. Paradoxically, however, the progress which enabled the detection of tiny LM has generally resulted in a restriction of the indications for hepatectomy because the resection of more than 10 or 15 bilateral LM is usually considered surgically unfeasible.

The recent introduction of liver radiofrequency ablation (RFA) allowing intraoperative destruction of small-sized LM, may be a new tool for the liver surgeon with the main advantage of sparing normal liver parenchyma. The percutaneous approach is minimally invasive but only 3 or 4 limited sized LM can be treated. The per-laparoscopic use of RFA allows treatment of a few additional but also limited

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sized LM, and is still a palliative approach [START_REF] Mazzaglia | Laparoscopic radiofrequency ablation of neuroendocrine liver metastases: a 10-year experience evaluating predictors of survival[END_REF]. To date, the putative role of RFA integrated into the surgical setting has not been evaluated.

The aim of this retrospective review of a prospectively collected database was to report on the feasibility and the early survival results of a maximally cytoreductive hepatectomy combined with multiple RFA in one session to treat patients presenting more than 15 bilateral LM. This approach is a logical extent of the guidelines concerning maximal cytoreduction of GEPEC metastases.

Patients and methods:

Selection Criteria

All the data concerning patients with more than 15 LM from a GEPEC who underwent surgical resection or RF ablation of LM, were prospectively collected in a database.

All LM seen on imaging were considered (but not lesions discovered in the pathological specimen).

The preoperative work-up included pathological confirmation of the diagnosis of welldifferentiated GEPEC, and staging of the primary tumor. All patients underwent somatostatin analog receptor scintigraphy, a CT-scan of the thorax, abdomen, pelvis and determination of relevant blood markers. The number, size and location of the LM were determined on liver ultrasound, MRI and CT-scan including the hepatic arterial phases [START_REF] Dromain | MR imaging of hepatic metastases caused by neuroendocrine tumors : comparing four techniques[END_REF]. Volumetric CT-scan was also used to estimate liver volumes.

When the estimated remnant liver volume was less than 30% of the total liver volume, preoperative portal vein embolization was performed [START_REF] Roche | Pre-operative portal vein embolisation for hepatic metastases[END_REF][START_REF] Elias | Preoperative selective portal vein embolization before hepatectomy for liver metastases: long-term results and impact on survival[END_REF].

The treatment was decided at a multidisciplinary team meeting during which all imaging studies were reviewed with the radiologists. All the patients were operated on during the 4 weeks following the last imaging work-up. Only patients with a good general status (WHO Performance Status < 2) and therefore, able to undergo major liver resection, were included in this study. The spontaneous slope of tumor growth before liver surgery was low [less than 20% of progression over 6 months] (8), which excluded patients with rapidly progressive disease. Small extra-hepatic metastases limited to bone were not considered an exclusion criterion (given that the short-term prognosis of the patient was based on the liver tumor burden). The detection of LM

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on ultrasound was a further requirement. No chemotherapy nor biotherapy was given before surgery, nor as adjuvant treatment after surgery.

Surgical procedures

The aim of the surgical procedure was to resect all LM but also extra-hepatic tumor sites including the primary tumor (which could have necessitated a pancreaticoduodenectomy, splenopancreatectomy, or intestinal resection), and lymph nodes.

After complete exploration of the abdominal cavity, the liver was meticulously explored following complete mobilization of the two lobes and an ultrasound examination enabled us to produce a precise drawing of the lesions (locations and sizes of the LM).

All LM exceeding 2.5 cm had to be resected as they could not be safely RF ablated.

LM smaller than 2.5 cm could be resected or RF ablated. Hepatectomy was systematically performed under intermittent complete vascular exclusion of the liver, without interrupting inferior vena caval flow [START_REF] Elias | Intermittent exclusion of the liver without vena cava clamping during major hepatectomy[END_REF], after intermittent vascular clamping of the hepatic pedicle and all the hepatic veins (excepted those of the Spiegel lobe).

The definition of an extended hepatectomy was applicable when at least four Couinaud liver segments were resected. RFA was performed with Valleylab cool-tip RF electrodes (Gosport, PO, USA) which come in 3 sizes (1 cm, 2 cm, and 3 cm) and are used according to the diameter of each metastasis. RFA was performed after the hepatic resections, under ultrasonographic guidance, working clockwise, from right to left, first ablating deep-seated LM and finishing with the superficial lesions. The surgeon constantly referred to drawing indicating the sites and sizes of LM produced following ultrasound detection before RFA. Simple RFA sessions were performed [START_REF] Elias | Intraoperative use of radiofrequency treatment allows an increase in the rate of curative liver resection[END_REF], but when necessary, the central bile ducts were also cooled to protect them from heat (a technique we described in 2001) [START_REF] Elias | Intraductal cooling of the main bile ducts during intraoperative radiofrequency ablation[END_REF][START_REF] Elias | Intraductal cooling of the main hepatic ducts during radiofrequency ablation prevents biliary stenosis[END_REF], or a trans-RF hepatectomy was performed after RF destruction of one or several LM located along a suitable transection line, in order to spare as much normal parenchyma as possible (a technique we described in 2002) [START_REF] Ouellet | Transmetastasis curative liver resection immediately following radiofrequency destruction[END_REF][START_REF] Elias | The trans-metastasis hepatectomy (through metastases previously ablated with radiofrequency): results pf a 13case study of colorectal cancer[END_REF]. Patients underwent a postoperative CTscan before being discharged from hospital.

Statistics

Usual arithmetic was use for medians and means. Survival curve was done with the Kaplan-Meyer method.

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Results

Patients

Sixteen patients underwent this one-step extensive surgery including the treatment of a minimum of 15 bilateral LM, from January 2002 to May 2007. There were 7 males and 9 females with a mean age of 48 ± 10 years (median: 52, range: 30-61). The primary was located in the pancreas or duodenum in 10 patients (including 2 gastrinomas, 1 insulinoma, 1 glucagonoma and 1 vipoma), in the small bowel in 4 patients, and in the bronchus in 2 patients. During the preoperative work-up, the primary tumor was present in 9 patients, residual invaded lymph nodes were present in the area of the previous primary tumor resection in 3 patients, and asymptomatic small bone metastases were present in 3 patients (but not considered as contraindication to the liver procedure, the short term prognostic being based on the liver tumor burden)..

Procedures

Four patients underwent preoperative selective portal embolization. Nine major hepatectomies were performed. Extra-hepatic resections were associated with six of the 9 major hepatectomies, and with all the minor hepatectomies. Thus, associated resections were performed in 13/16 patients. Of note, extra-hepatic resections were mainly performed on the duodenopancreas (table 1). A mean of 2.3 supplementary LM per patient were discovered through palpation or ultrasonography at laparotomy. The surgical and RFA procedures are described in table 1. In brief, surgical resections with anatomical and non anatomical liver surgery treated a mean of 15.3 ± 8.9 LM (median: 12, range:3-59), while RFA treated a mean number of 11.6 ± 8.4 LM (median 10, range 0-30) per patient. The mean size of RF-ablated LM was 13 ± 11 mm (range: 4-27). Three bile duct cooling procedures and 5 trans-RFA hepatectomies were required.

Finally, a median of 23 LM per patient (range 15-89; mean 25.7 ± 12) were treated with surgery combined with RFA. Approximately 60% of the LM were surgically excised, and 40% were RF ablated. The mean duration of surgery was 5h32 min, and median intra-operative blood loss was 510 ml.

T P I R C S U N A M D E T P E C C A ARTICLE IN PRESS 7 Postoperative course (table 2)
No mortality occurred. Morbidity was observed in 10 patients (62.5%). The following surgical complications were recorded : hemorrhage (n=1), biliary peritonitis requiring re-operation (n=1), pleural effusion requiring drainage (n=4), pancreatic fistula (n=3), transient liver insufficiency with ascites (n=2), subphrenic hematoma (n=1) and inferior vena caval thrombosis (n=1). The following medical complications were documented : lung infection (n=3), urinary infection (n=4), and myocardial infarction (n=1). This resulted in grade 4, grade 3 and grade 2 complications (NCI classification) in 2, 4 and 5 patients respectively. Among the 13 patients who underwent hepatic and extra-hepatic resections, 8 experienced at least one postoperative complication. Postoperative complications were equally divided between the 2 groups of major and minor hepatectomies. Lately, no stenosis of the central bile ducts has been observed for the three patients in whom the bile duct cooling was used.

The mean duration of hospitalization was 16.6 ± 4.8 days (median: 15, range: 10-24).

The five patients who presented symptoms in relation with tumor secretion were free of symptoms after surgery.

Follow-up, survival rate

Follow-up was not the chief objective of this feasibility study. It was conducted every six months with a liver ultrasound and MRI, associated with somatostatin analog receptor scintigraphy. After a median follow-up of 27 months, 12 patients relapsed (8 of them inside the liver) and two patients died. The overall survival rate was 84% at 3 years (figure 1).

Discussion

Rational. To date, it has not been possible to conduct a randomized study focused on the place of hepatectomy in the treatment of LM from well-differentiated GEPEC. So, following the results of numerous non randomized studies which showed that surgical therapy is still the most efficient way to treat metastatic disease, offering the longestlasting benefits and the best quality of life (2-7), all the guidelines for the management of neuroendocrine tumors recommend the removal of LM, when possible and resection of at least 90% of the disease (19-21). The crucial point about

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surgery of LM from well-differentiated GEPEC is patient selection. A multivariate study of 118 patients with metastatic GEPEC treated in our institute taught us that the three main prognostic factors are age (>65 year), more than 10 LM, and a low natural tumor burden slope [START_REF] Malka | Prognostic factors of metastatic welldifferenciated gastroenteropancreatic endocrine tumors[END_REF]. Most teams propose surgery to patients presenting only a few LM or unilobar LM. Different surgical teams use diverse selection criteria and resection techniques. Finally, liver resection series exclusively concern small groups of highly selected patients, and the majority of the other patients presenting with numerous and bilateral LM are not selected for surgery.

The first objective of our work was to expand the indications for liver surgery and to operate on a greater proportion of patients in the subgroup exhibiting a low natural tumor burden slope and a good general status. Our series represent only an extensive application of the international guidelines concerning the survival benefit of maximal cytoreduction of the metastatic disease for GEPEC (19-21).

Feasibility and preliminary survival results. Our feasibility study shows that partial hepatectomy resecting large or contiguous LM combined with extensive use of optimized RF ablating the remaining small LM, allowed us to treat 16 selected patients bearing a median of 23 LM per patient, in a single surgical session, with 40 % of the LM being treated with RFA. No mortality occurred, however, significant but still acceptable morbidity was observed. It is too early to determine a possible benefit in terms of long-term survival, but early results are encouraging. Effectively, when the survival curves of these 16 patients bearing a median of 23 LM per patient are compared with those of the 47 hepatectomized patients with GEPEC LM bearing a median number of 7.4 LM per patient that we published in 2003 [START_REF] Elias | Liver resection (and associated extrahepatic resections) for metastatic well-differenciated endocrine tumors: a 15year single center prospective study[END_REF], the overall survival (figure 2) and disease-free survival rates (figure 3) are similar. To date, this median number of 7.4 LM resected per patient is the highest reported in the literature [START_REF] Elias | Liver resection (and associated extrahepatic resections) for metastatic well-differenciated endocrine tumors: a 15year single center prospective study[END_REF]. In the present series of highly selected cases, the median number was 23. In other words, with this new approach we succeeded in obtaining the same survival rates for patients bearing more numerous and bilateral LM, whose disease extent was not initially amenable to resection. So, it was possible to upgrade treatment for these patients and ultimately improve their early survival. It also seems that, being able to turn the clock back to zero for all detectable tumor disease, results in a similar survival duration, whatever the number of LM from GEPEC. The major criticism to

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our series is to do not present a control group. However, until now, none randomized study could be conducted concerning the treatment of LM from GEPEC.

The high postoperative complication rate in our series could be considered debatable. However, it includes all grades of complications, there were no postoperative deaths, and this approach allowed these selected patients to leave the poor prognosis group of unresectable patients whose 5-year survival rate was only 22% in the US Modlin and Sandor database [START_REF] Modlin | An analysis of 8305 cases of carcinoid tumors[END_REF].

Technical aspects. Various surgical approaches have been proposed to treat a high number of LM, in one or two sessions. A two-step surgical procedure was recently described to treat a higher number of [START_REF] Adam | Two-stage hepatectomy: a planned strategy to treat irresectable liver tumors[END_REF][START_REF] Jaeck | One or two-stage hepatectomy combined with portal vein embolization for initially nonresectable colorectal liver metastases[END_REF], but only a few cases were reported and the mean number of LM resected during the two steps never exceeded fifteen [START_REF] Adam | Two-stage hepatectomy: a planned strategy to treat irresectable liver tumors[END_REF][START_REF] Jaeck | One or two-stage hepatectomy combined with portal vein embolization for initially nonresectable colorectal liver metastases[END_REF]. It is noteworthy that these two-step procedures incur a cost in terms of risk, pain, hospitalization and have social and economic repercussions. An alternative approach is to use the entire range of tools currently available to treat these patients in one step, as presented in our series. In our opinion, the only indication for the above-mentioned two-step surgical procedure is when both a major hepatectomy and a duodenopancreatectomy have to be performed since this surgical situation is known to be associated with high morbidity (91%) and mortality (14 to 47%) [START_REF] Ota | Operative outcome and problems of right hepatic lobectomy with pancreatoduodenectomy for advanced carcinoma of the biliary tract[END_REF][START_REF] Ebata | Right hepatopancreatoduodenectomy: improvements over 23 years to attain acceptability[END_REF].

In such cases, we first resect the primary and the LM in the less tumorous part of the liver, while the second step is devoted to removing the LM remaining in the more tumorous part of the liver. This report presents an integrated approach aimed at improving the number of treatable hepatic metastases. We use a great number of different tools currently available in the liver surgery setting : preoperative interventional therapy, intraoperative imaging and intraoperative RFA with new techniques like bile-duct cooling or the trans-LM liver section (these LM are ablated with RF before surgery).

Our experience, based on more than 1300 hepatectomies for malignant tumors and more than 250 intraoperative uses of RFA, has taught us the following technical points. First, complete mobilization of the liver is necessary to perform a meticulous exploration of the organ and to operate under safe conditions. Second, bloodless hepatectomy is a prerequisite before using multiple RF ablations in the remaining liver in order to decrease the risk of liver failure. We systematically perform this

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Statement of the contribution of each author:

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FiguresFigure 1 :

 1 Figures

Figure 2 :

 2 Figure 2: Comparison of the overall survival curves of a personal historical group of hepatectomized patients (with a median of 7 LM per patient) 7 and the present group of patients (with a median of 23 LM per patient).

Figure 3 :

 3 Figure 3: Comparison of the disease-free survival curves of a personal historical group of hepatectomized patients (with a median of 7 LM per patient) 7 and the present group of patients (with a median of 23 LM per patient).

Table 1 -

 1 Surgical and RFA Procedures

		Hepatectomy (Type)	RFA (number)	Extra-hepatic resection	Blood loss (ml)	Operative time (min)
		Left Hep. + 2 LM ¶	7	Splenopancreatectomy	200	330
				Diaphrag m+ Bilat
		Left Hep	10	Oophorectomy + appendicectomy+	400	360
				lymphadenectomy SMA*
		Right Hep	11	Appendicectomy	950	450
		Left Hep	28	Splenopancreatectomy	500	315
	Major hepatectomy	Right Hep + 2 LM	3	Splenopancreatectomy	300	310
		Right Hep	7	Appendicectomy	300	300
		Right Hep	3	-	500	270
		Extended
		Right Hep +	7	-	600	330
		1LM
		Right Hep	4	-	750	300
		Bisegment V-VI	16	Right colectomy	250	300
		2 LM	16	Paraganglioma	300	315
		Bisegment II -III	30	Splenopancreatectomy	270	1000
	Minor hepatectomy	Segment II + 1 LM	19	Duodenotomy	350	420
		4 LM	16	Duodenopancreatectomy 600	450
		Bisegment II -III + 2LM	11	Appendicectomy	600	180
		1LM	9	Duodenopancreatectomy 200	450
	¶LM : limited resection of liver metastases

*SMA : Superior Mesenteric Artery

bloodless hepatectomy achieved through transient intermittent total vascular exclusion of the liver without interrupting inferior vena caval flow. Third, the extensive repeated use of intraoperative ultrasound is mandatory. When multiple RF ablations are required, a precise drawing indicating the sites and sizes of the LM is useful to guide repeated RFA. Each of the previously ultrasound identified LM are ablated, one by one, and noted as "treated" on the drawing. When a part of the liver is temporarily saturated with gaseous micro-embols, we leave it for 10-15 min before resuming RF ablation in that part, and another part of the liver is treated during that interval.

Particular techniques like bile-duct cooling or the trans-RF hepatectomy passing through an ablated LM (in order to spare parenchyma for volumetric reasons) are useful. Their safety and efficacy have already been proven [START_REF] Elias | Intraductal cooling of the main hepatic ducts during radiofrequency ablation prevents biliary stenosis[END_REF][START_REF] Elias | The trans-metastasis hepatectomy (through metastases previously ablated with radiofrequency): results pf a 13case study of colorectal cancer[END_REF] and the location of LM is no longer a limit to RFA. Fourth, due to the high number of RF ablations in the remaining part of the liver, maximum sparing of normal parenchyma is critical :

RFA must be as limited as possible in volume and optimally adapted to the size of the LM. Fortunately, numerous LM from endocrine tumors are small, round, and easily detectable because they are strongly hyperechogenic. This is why in most cases, we only used probes with an electrode length limited to 10 mm or 20 mm. The liver volume reduction resulting from these multiple RF ablations, even when limited in size, is difficult to predict. Our inability to precisely predict this reduction explains the occurrence of two cases of transient liver failure and we are awaiting a 3-D volumetric reconstruction program usable on MRI in order to be able to appraise the real volume of functional liver parenchyma with greater safety margins.

In conclusion, by combining bloodless hepatic resection with the extensive use of RFA, selected patients presenting a median of 23 LM per patient can be curatively treated in a single-step surgical procedure. Thus, the therapeutic approach is "upgraded" and patient early survival rates are improved, and similar to those obtained by conventional hepatectomy.

The authors thank Ms Lorna Saint Ange for editing.

Conflict of interest statement:

The authors state that they have no conflict of interest.


I Barner-Rasmussen
email: ian.barner-rasmussen@helsinki.fi

P Popov

T Böhling

C Blomqvist

E Tukiainen

Microvascular reconstructions after extensive soft tissue sarcoma resections in the upper limb

Keywords: Sarcoma, Reconstructive surgery, Surgical flaps, Upper extremity, Microsurgery, Replantation

Aims: Limb-sparing surgery combined with radiotherapy (RT) is the basis of extremity soft tissue sarcoma (STS) treatment. The aim of this study was to evaluate the results of microvascular reconstruction after extensive tumour resections in the upper extremity.

Methods: 20 patients with STS of the upper extremity were treated with excision and microvascular reconstruction. RT was administered if surgical margins were less than 25mm.

Results were evaluated retrospectively.

Results: 20 free flaps were performed and no flaps were lost. There was no operative mortality, and wound complication rate was 15%. Median follow-up length was 74 months.

Five-year local recurrence-free survival was 57%, metastasis-free survival 67%, disease-free survival 45% and disease-specific overall survival 80%. Ten patients had no or only mild impairment of upper extremity function, seven had impaired function affecting daily life, and three patients underwent amputation. For patients treated with curative intent, limb salvage rate was 94%.

Conclusions:

Free flaps are useful and reliable in the treatment of patients with STS of the upper extremity. Without microvascular reconstruction limb salvage would have been impossible in these patients. Oncological outcome is comparable to other extremity STS patients and upper extremity function is acceptable.

Introduction

Soft tissue sarcomas (STS) are a rare, heterogeneous group of tumours. In 2000-2005 the mean age-adjusted incidence rate of STS in Finland was 2.0/100 000, accounting for less than one per cent of adult malignancies [1]. 12 to 15 per cent of STS are located in the upper extremity [START_REF] Nijhuis | Epidemiological aspects of soft-tissue sarcomas (STS) -consequences for the design of clinical STS trials[END_REF][START_REF] Pollock | The National Cancer Data Base report on soft tissue sarcoma[END_REF].

In the past, extremity STS was often treated with amputation due to high rates of local recurrence after simple resection [START_REF] Cantin | The problem of local recurrence after treatment of soft tissue sarcoma[END_REF][START_REF] Hoekstra | Role of surgery as primary treatment and as intervention in the multidisciplinary treatment of soft tissue sarcoma[END_REF]. Today, using a combination of surgery and radiotherapy (RT), better functional results are achieved with equal rates of local control [START_REF] Rosenberg | The treatment of soft-tissue sarcomas of the extremities: prospective randomized evaluations of (1) limb-sparing surgery plus radiation therapy compared with amputation and (2) the role of adjuvant chemotherapy[END_REF][START_REF] Yang | Randomized prospective stydy of the benefit of adjuvant radiotherapy in the treatment of soft tissue sarcomas of the extremity[END_REF].

Modern treatment consists of a multidisciplinary team approach, and limb-sparing surgery combined with oncological treatment [START_REF] Clark | Soft-tissue sarcomas in adults[END_REF].

The required surgical margins of 2-3cm [START_REF] Sampo | Impact of the smallest surgical margin on local control in soft-tissue sarcoma[END_REF] of tumour-free tissue frequently cause large defects, and local or free flaps are often required to achieve tension-free wound closure or to reconstruct tissue defects. Free flap reconstruction is needed in 11-18% of patients undergoing limb-sparing surgery for upper extremity STS [START_REF] Kim | Upper extremity limb salvage with microvascular reconstruction in patients with advanced sarcoma[END_REF][START_REF] Lohman | Soft tissue sarcoma of the upper extremity: a 5-year experience at two institutions emphasizing the role of soft tissue flap reconstruction[END_REF][12]. Limb salvage is not always possible, and sometimes amputation is unavoidable [START_REF] Clark | Amputation for soft-tissue sarcoma[END_REF]. For selected cases of proximal upper extremity or shoulder girdle tumours, even forequarteramputation is used for curation or for palliative treatment [START_REF] Clark | Major amputation for soft-tissue sarcoma[END_REF]. When simultaneous chest wall reconstruction is necessary, fillet flaps from the amputated extremity are useful for reconstruction [START_REF] Tran | Free fillet extremity flap: indications and options for reconstruction[END_REF][START_REF] Cordeiro | The role of microsurgery in reconstruction of oncologic chest wall defects[END_REF]. For tumours requiring segmental resection of an extremity, heterotopic replantation has been used [START_REF] Windhager | Resection-replantation for primary malignant tumours of the arm. An alternative to fore-quarter amputation[END_REF].

The aim of this study was to evaluate the results of a single institution in using microvascular reconstruction for extensive bone and soft tissue defects after tumour resections in the upper extremity.

Sarcoma group protocol

Preoperatively, diagnosis is confirmed by fine or core-needle biopsies, and radiological examinations (CT, MRI) performed to define local and systemic status of the disease. Before sample fixation the pathologist measures tumour size and final histopathological examination is then carried out. STS malignancy grading is based on a four-tiered grading system used by the Scandinavian Sarcoma Group. Grades 1-2 are considered low malignancy grade, and 3-4 are considered high grade. Based on the work of Broders, the system considers cellularity, cell and nuclear polymorphism, differentiation, necrosis, haemorrhage, mitotic activity, and growth pattern for tumour grading [START_REF] Angervall | Principles for pathologic-anatomic diagnosis and classification if softtissue sarcomas[END_REF][START_REF] Broders | Pathologic features of soft tissue fibrosarcoma with special reference to the grading of its malignancy[END_REF].

Wide microscopical margins are defined as ≥ 25mm of healthy tissue or an intact fascial barrier separating the tumour from the excision margin. When margins are less than wide but no tumour cells are found at the edges of the specimen, excision is defined as marginal.

Intralesional margins should lead to re-excision in patients treated with curative intent. After marginal excision, external beam radiotherapy (EBRT) is delivered to the operative field with a dose of 50 Gy during 5 weeks. Selected patients receive adjuvant chemotherapy. Follow-up time was five years for STS patients provided there were no recurrences.

Patients with high-grade disease were examined every second month for the first two years, and then every six months. Follow-up protocol for low-grade disease was clinical examination

Patient material

In 1987-2006 the HUCH soft tissue sarcoma group treated 1314 STS patients, of which 204 had upper extremity tumours. 24 of upper extremity STS patients were treated with primary amputation, and direct closure after tumour excision was done in 82 patients.

Reconstructive procedures were skin graft in 28, pedicled skin flap in 15 and pedicled muscle flap in 33 patients. 20 patients required microvascular reconstruction after soft-tissue tumour excision, and they were included in this study (Table 1). Two patients had palliative procedures for metastasized STS, and they were excluded from oncologic analyses, but included in analyses for surgical endpoints and functional outcome. Two patients, one with dermatofibrosarcoma protuberans (DFSP) and the other with desmoid tumour, were also excluded from oncologic analyses but included in surgical endpoint and functional outcome analyses. 16 patients thus remained for analysis of oncologic endpoints.

In all, there were 20 patients (4 male, 16 female) with a median age of 61 years. Seven patients were referred for virgin primary tumours and six for primary tumours after intralesional operation. Seven patients were admitted for recurrent tumours.

Tumour characteristics

Median tumour size was 5.0 cm (range 1.8-29.0). Excluding the two patients treated with palliative intent, all tumours were less than 10.0 cm in diameter. 16 soft tissue sarcomas were of high malignancy grade and two were of low grade. 17 tumours were extracompartmental and three were intracompartmental; all of the intracompartmental tumours were subcutaneous.

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6 16 tumours were located distal to the elbow joint. In one patient the joint was affected and in three cases the tumour was located above elbow level. Malignant fibrous histiocytoma (MFH) was the most common histological STS subtype, present in ten cases. Other diagnoses were two fibrosarcomas, two synovial sarcomas, and one sarcoma NOS, extraskeletal chondrosarcoma, epitheloid sarcoma and malignant peripheral nerve sheath tumour (MPNST).

Reconstructive procedures

All operations were performed as single-stage procedures. Simple tumour excision and microvascular reconstruction of the defect was done for 17 patients. The free flap contained bone in three of these. Two forequarter-amputations with fillet flaps from the amputated extremity were performed. In one of these, the fillet flap was also used for chest wall reconstruction. In addition, a patient with synovial sarcoma affecting the elbow joint had replantation of the distal forearm to the upper arm after segmental resection of the elbow area.

Tendon reconstruction was performed in eight cases, and nerve reconstruction in six cases. In addition one latissimus dorsi flap was used as an innervated functional flap, the motor nerve of the flap sutured to the radial nerve at the recipient site. Recipient site skin grafting was necessary in two cases.

Median duration of operation was 310 minutes (range 195-575) and median flap ischemia time was 64 minutes (range 31-216). Median perioperative bleeding was 650 ml (range 150-8000).

M A N U S C R I P T A C C E P T E D ARTICLE IN PRESS 7

Surgical margins

For curatively treated STS patients, wide microscopical margins were achieved in seven patients, and marginal excision in eight patients. In one patient, final histopathological examination showed intralesional margins, and humeral amputation was performed.

Oncological treatment

Five patients with wide surgical margins had no oncological treatment. Eight STS patients with marginal excision underwent postoperative external beam radiotherapy (EBRT). In addition, two patients with wide excision received postoperative EBRT. Preoperative radiotherapy was given to one patient with a large, high-grade tumour. This patient was also the only one to receive chemotherapy, which was given both as neoadjuvant and adjuvant treatment. In three cases, including the two palliatively treated patients, EBRT could not be used because of earlier radiotherapy. One patient with osteoradionecrosis and subsequent fistula at nine months was treated with repeated wound revisions. Successful closure was achieved at 14 months after coverage with a pedicled flap. Later remodelling of the flap was carried out in three cases to achieve a more satisfactory aesthetic or functional result. The patient that had undergone humeroantebrachial replantation had surgery at four months to adjust the position of the replant for better function. No significant prognostic factors predicting surgical complications were identified in statistical analysis.

Statistical analysis

SPSS for

Oncologic outcome

Oncologic outcome was analyzed in 16 soft-tissue sarcoma patients treated with curative intention. Median length of follow-up was 74 months (range 19-187). Five-year estimated local recurrence-free survival (LRFS) was 57%, metastasis-free survival (MFS) 67% and disease-free survival (DFS) 45%. Disease-specific overall survival (DSOS) was 80% at five years (Figure 1).

Seven patients developed a local recurrence at a median of 37 months (range 6-61).

Patients with >5.0 cm tumours were significantly more likely to have a local recurrence than

M A N U S C R I P T A C C E P T E D ARTICLE IN PRESS

9 those with 5.0 cm or smaller tumours (LRFS 20% vs. 78%, P=0.004). Local recurrence was also more likely for higher-grade tumours; LRFS for grade 2 tumours was 100%, for grade 3 tumours 67%, and for grade 4 tumours 29% (P=0.021). Metastasis developed in seven patients. Median time to metastasis was 33 months (range 4-117). Seven out of 16 patients have died of disease, at a median of 72 months (range 21-187) after surgery. Tumour size over 5.0 cm was a significant predictor of disease death (DSOS 60% vs. 91% for patients with 0-5.0 cm tumours, P=0.028)

The two patients who underwent palliative surgery for advanced STS both died from disease, at two and 13 months. The two patients operated for DFSP and desmoid tumour are both disease free at a 112 and 133 months, respectively.

Functional outcome

Eight patients experienced no impairment of function in the upper extremity during followup. Two patients experienced some impairment of function not affecting daily activities. Seven patients had impaired upper extremity function significantly affecting daily activities. Two patients underwent planned primary forequarter amputation, and humeral amputation was performed in one patient due to intralesional surgical margins.

Because of local recurrences at one, two and four years after free flap sarcoma surgery, late amputations were necessary in three patients. Excluding the two planned forequarter amputations this gives an early limb salvage rate of 94%, and 78% limb salvage rate at five years. In all, five amputations were performed in curatively treated patients.

M A N U S C R I P T A C C E P T E D ARTICLE IN PRESS 10

Discussion

Soft tissue sarcoma of the upper extremity is rare; only few cases are encountered annually in Finland with 5.3 million inhabitants [1]. Microvascular reconstructive surgery after sarcoma resection is required in a significant proportion of these patients, but remains a procedure that few surgeons become familiar with. This is, to our knowledge, the largest series to date on upper extremity STS focusing on limb salvage and free flap reconstruction.

Limb salvage and upper extremity reconstruction

Oncologically safe surgical margins, preserving a functional limb and a good aesthetic result are the goals of limb salvage surgery for STS. Limb salvage does not adversely affect oncological outcome [START_REF] Rosenberg | The treatment of soft-tissue sarcomas of the extremities: prospective randomized evaluations of (1) limb-sparing surgery plus radiation therapy compared with amputation and (2) the role of adjuvant chemotherapy[END_REF][START_REF] Yang | Randomized prospective stydy of the benefit of adjuvant radiotherapy in the treatment of soft tissue sarcomas of the extremity[END_REF], and the functional benefits of limb salvage with soft tissue reconstruction in sarcoma surgery have been established [START_REF] Serletti | Functional outcome after soft-tissue reconstruction for limb salvage after sarcoma surgery[END_REF]. Free flaps provide wellvascularised tissue facilitating wound healing, and also tolerate radiotherapy well. In addition, no further morbidity is caused to the extremity. A wide array of free flaps is available for reconstruction following upper extremity tumour resection, and the choice of flap is based on defect size, types of tissue required, postoperative functional goal, and surgeon preference.

For reconstruction of long segments of bone, the free fibular flap is preferred [START_REF] Saint-Cyr | Reconstruction of the hand and upper extremity after tumor resection[END_REF][START_REF] Pederson | Upper extremity microsurgery[END_REF].

Disease recurrence and survival

Follow-up in this series was long, with a median follow-up of 74 months, attributable to the centralized care of these patients. Oncological results were comparable to studies with similar patient material [START_REF] Sampo | Impact of the smallest surgical margin on local control in soft-tissue sarcoma[END_REF]. Other works on upper extremity STS have reported rates of local recurrence of 17-25% with variable lengths of follow up [START_REF] Lohman | Soft tissue sarcoma of the upper extremity: a 5-year experience at two institutions emphasizing the role of soft tissue flap reconstruction[END_REF]12,[START_REF] Herbert | Limbpreserving treatment for soft-tissue sarcomas of the extremities. The significance of surgical margins[END_REF]. In a study including 80 patients with STS of the upper extremity treated at the authors' institution between 1987 and 1999, local recurrence was less common (LRFS 79%), but MFS and DSOS were comparable to the present study [12]. Only 19% of patients in the earlier study presented with recurrent tumour compared to 35% in this series, which may explain our higher rate of local recurrence; [START_REF] Pisters | Analysis of prognostic factors in 1,041 patients with localized soft tissue sarcomas of the extremities[END_REF]. Kim et al reported their results in treating 17 patients with limb salvage and microvascular reconstruction [START_REF] Kim | Upper extremity limb salvage with microvascular reconstruction in patients with advanced sarcoma[END_REF]. We have reported very similar outcomes, the slightly lower LRFS and DSOS (50.0 and 61.3%, respectively) of Kim et al likely explained by their more challenging patient material with mostly high-grade, recurrent sarcomas.

Functional outcome

A variety of scoring systems have been used for functional evaluation after upper extremity tumour surgery [START_REF] Wright | Functional and Oncological outcomes after limb-salvage surgery for primary sarcomas of the upper limb[END_REF][START_REF] Hoy | Reconstruction of musculoskeletal defects following oncologic resection in 76 patients[END_REF]. Limb salvage and microvascular reconstruction did not adversely affect functional outcome in a previous study after upper extremity STS resection [27]. Due to the retrospective nature of this study, quantitative tools for assessment of functional outcome were unavailable, but the majority of our patients experienced normal or only mildly impaired upper extremity function.

Further treatment options

In the future, techniques like composite tissue allotransplantation, or advanced myolectric prostheses, combined with targeted reinnervation surgery, or dielectric elastomers [28-30] could provide us with readily available, easy-to-use components for reconstruction of the upper extremity. At present these remain, however, experimental techniques, and locally available tissue, or of pedicled or free flaps must be used for reconstruction.

  Patients treated by the Helsinki University Central Hospital (HUCH) soft tissue sarcoma group who had undergone microsurgical reconstruction after upper limb soft tissue tumour surgery in 1990-2006 were identified, and their medical records retrospectively reviewed.Data concerning patient demographics, tumour characteristics, surgical treatment and oncologic and functional outcome were collected from hospital records

  times annually. A chest X-ray was taken at each visit. A CT or MRI scan of the operative area was performed annually, beginning at six months postoperatively.

8 Results

 8 Windows (v 15.0, SPSS Inc., Chicago, Illinois) was used for statistical analysis.Oncologic endpoints were: local recurrence-free survival (LRFS), metastasis-free survival (MFS), disease-free survival (DFS) and disease-specific overall survival (DSOS), calculated by the Kaplan-Meier method. Values refer to outcome at five years. Prognostic factors for surgical complications were analyzed with chi-square-and Fisher's exact test. P-values of ≤0.05 were considered significant.Flap survival and complicationsThere was no postoperative mortality and no free flaps were lost. One patient required immediate reoperation for reanastomosis of the flap vein (Patient 17). Another patient underwent donor site haematoma evacuation on the first postoperative day (Patient 7). In one case, reosteosynthesis of the fibula flap was performed the day after the initial operation (Patient 5). Wound revision was necessary in two patients for minor wound complications (Patients 17 and 20). In all, three patients had wound complications requiring one or more operative procedures, giving a wound complication rate of 15%.

  presentation has been shown to predict further local recurrences

ConclusionsFigure 1 .

 1 Figure captions:

Table 1

 1 Patient and tumour characteristics

	Patient Tumour histology	Grade Size	Free flap	DSOS (months) Status
	1 a	MFH	4	20.0	latissimus dorsi	2	DOD
	2 a	extraskeletal chondrosarcoma 3	29.0	fillet (antebrachium) b	13	DOD
	3	MFH	4	8.0	fillet (antebrachium) b	26	DOD
	4	MFH	4	4.5	tensor fascia latae	31	DUC
	5	MFH	4	7.0	fibula	40	DOD
	6	sarcoma NOS	2	1.8	scapular	87	NED
	7	MFH	4	6.0	latissimus dorsi	58	NED
	8	synovial sarcoma	3	5.0	antebrachial replantation	21	DOD
	9	fibrosarcoma	3	6.0	radial forearm	72	DOD
	10	MFH	4	9.0	tensor fascia latae	62	DUC
	11	MFH (myxoid)	2	5.0	radial forearm	76	NED
	12	MPNST	4	2.5	anterolateral thigh	31	NED
	13	epitheloid sarcoma	3	3.0	latissimus dorsi	187	DOD
	14	synovial sarcoma	3	3.0	fibula	165	NED
	15	desmoid tumor c	-	5.8	scapular	112	NED
	16	MFH	3	2.5	radial forearm	96	NED
	17	MFH	4	4.5	latissimus dorsi	155	NED
	18	MFH	3	4.5	tensor fascia latae + crista iliaca	145	DOD
	19	DFSP c	1	3.0	radial forearm	133	NED
	20	fibrosarcoma	3	5.0	latissimus dorsi	130	DOD

MFH: malignant fibrous histiocytoma, NOS: not otherwise specified, MPNST: malignant peripheral nerve sheath tumour, DFSP: dermatofibrosarcoma protuberans. DSOS: disease-specific overall survival. DOD: dead of disease, DUC: dead of unrelated cause, NED: no evidence of disease. a Palliative treatment intent. b Primary amputation. c Non-sarcoma, excluded from oncological endpoint analyses.

Finnish Cancer Registry. Cancer in Finland

and

Cancer Society of Finland, Publication No. 72. Helsinki, 2007.

Popov P, Tukiainen E, Asko-Seljavaara S, Huuhtanen R, Virolainen M, Virkkunen P et al. Soft tissue sarcomas of the lower extremity: surgical treatment and outcome. Eur J Surg Oncol 2000; 7:

Acknowledgements

The first author was supported by a research grant from The Luise and Henrik Kuningas Foundation while working on this article. The funding source had no role in the preparation of the manuscript.

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17 27

M A N U S C R I P T A C C E P T E D ARTICLE IN PRESS

1

Conflict of interest statement

The authors declare that they have no conflict of interest.


G Martin-Canal

A Saavedra

J M Asensi

T Suarez-Zarracina

A Rodriguez-Guardado

E Bustillo

J Fierer

J A Carton

J Collazos

V Asensi

Meropenem monotherapy is as effective as and safer than imipenem to treat brain abscesses 

The efficacy of carbapenems versus cefotaxime (8 g/day) + metronidazole (1.5-2 g/day) [combined standard chemotherapy (CSC)] for the treatment of brain abscess was compared. Fifty-nine adult patients with brain abscesses received either imipenem or meropenem (3-4 g/day) or CSC for a mean of 5 weeks, in addition to neurosurgery in most cases. Cure was obtained in 84.7% of cases; 42/47 (89.4%) on carbapenems [18/22 (81.8%) on imipenem versus 24/25 (96.0%) on meropenem] and 8/12 (66.7%) on CSC (P = 0.06). Seven patients with multiple abscesses were treated with imipenem (1 died; cure rate 85.7%), five with meropenem (all survived; cure rate 100%) and five with CSC (2 died; cure rate 60%) (P < 0.4). Neurosurgery was performed in 43/59 cases (72.9%); 17 (77.3%) in the imipenem group, 21 (84.0%) in the meropenem group and 5 (41.7%) in the CSC group (P = 0.02). There was no significant difference in the rate of relapse requiring re-intervention. Treatment with meropenem was associated with a lower mortality than CSC (P = 0.026). Seizures were observed only with carbapenems [8/22 (36.4%) for imipenem versus 2/25 (8.0%) for meropenem; P = 0.03 . Carbapenems were more effective than CSC for treatment of brain abscesses. Because meropenem induced significantly fewer seizures than imipenem with at least the same clinical efficacy, the former appears to be a better choice to treat this infection.

A c c e p t e d M a n u s c r i p t

Introduction

Brain abscess is an uncommon infection of the central nervous system with a high morbidity and mortality. It is due primarily to direct spread from an infected paranasal sinus or ear, complication of a neurosurgical procedure or, more rarely, haematogenous dissemination, mostly from the lung and heart [START_REF] Mathisen | Brain abscess[END_REF][START_REF] Tseng | Brain abscess in 142 patients: factors influencing outcome and mortality[END_REF][START_REF] Carpenter | Retrospective analysis of 49 cases of brain abscess and review of the literature[END_REF]. It is usually caused by a mixture of microorganisms, with a high proportion of cases due to obligate anaerobes. Broad-spectrum -lactam antibiotics, and nowadays the combination of cefotaxime + metronidazole, are the standard therapy for empirical treatment of brain abscess, in addition to neurosurgery [START_REF] Sjölin | Treatment of brain abscess with cefotaxime and metronidazole: prospective study on 15 consecutive patients[END_REF][START_REF] Jansson | Efficacy and safety of cefotaxime in combination with metronidazole for empirical treatment of brain abscess in clinical practice: a retrospective study of 66 consecutive cases[END_REF].

Carbapenems penetrate well into the cerebrospinal fluid (CSF) and thus are a potential alternative to cephalosporins + metronidazole to treat brain abscesses [START_REF] Carton | Successful treatment of recurrent cerebral empyema and brain abscesses with imipenem[END_REF][START_REF] Meis | A brain abscess due to multiple-resistant Enterobacter cloacae successfully treated with meropenem[END_REF][START_REF] Asensi | Imipenem therapy of brain abscess[END_REF][START_REF] Modai | Penetration of imipenem and cilastatin into cerebrospinal fluid of patients with bacterial meningitis[END_REF]. However, some reports of imipenem-induced seizures, although infrequent, have limited its generalised use [START_REF] Asensi | Therapy of brain abscess with imipenem-a safe therapeutic choice?[END_REF][START_REF] Calandra | Factors predisposing to seizures in seriously ill infected patients receiving antibiotics: experience with imipenem-cilastatin[END_REF]. Meropenem has shown a much lower convulsive activity than imipenem while retaining the same broad antimicrobial spectrum [START_REF] Linden | Safety profile of meropenem: an updated review of over 6,000 patients treated with meropenem[END_REF][START_REF] Baldwin | Meropenem: a review of its use in the treatment of serious bacterial infections[END_REF][START_REF] Day | Correlation between in vitro and in vivo models of proconvulsive activity with the carbapenem antibiotics, biapenem, imipenem/cilastatin and meropenem[END_REF].

In this 11-year-old retrospective, non-randomised study, we compared the efficacy and safety of intravenous (i.v.) cefotaxime + metronidazole [combined standard chemotherapy (CSC)] with i.v. meropenem or imipenem monotherapy in addition to neurosurgery in the treatment of brain abscesses in adult patients admitted to the Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain.

A c c e p t e d M a n u s c r i p t 5

Patients and methods

Medical records from HUCA from January 1996 to December 2007 were retrospectively reviewed to identify cases of brain abscess. HUCA is a 1500bed tertiary university hospital in northwestern Spain providing neurosurgical coverage to a population of 1 100 000 people.

The diagnosis of brain abscess was made by microbiological, histological, radiographic, surgical and clinical findings as described previously [START_REF] Tseng | Brain abscess in 142 patients: factors influencing outcome and mortality[END_REF][START_REF] Asensi | Imipenem therapy of brain abscess[END_REF]. Brain abscess was diagnosed in 59 patients; surgically and histologically in 43 patients (40 of whom had positive microbiological cultures) and by compatible clinical picture and computed tomography (CT) or magnetic resonance imaging (MRI) findings in 16 patients who did not undergo neurosurgery. The mean incidence of brain abscess was of 4.9 cases/year. Forty-five patients were men and fourteen were women. The age range was 14-80 years (mean age 45.9 18.0 years). Patients with the following conditions were excluded from the study: (i) those who were immunocompromised or who tested positive for human immunodeficiency virus (HIV); (ii) those with subdural and epidural abscesses; and (iii) those with fungal, protozoal or mycobacterial abscesses.

Patients received different antimicrobial treatments in a non-randomised manner according to the preference of the infectious diseases consultant. From 2000 onwards, most of the patients were treated with a carbapenem in addition to neurosurgery. Antibiotics were usually started at the time of diagnosis of A c c e p t e d M a n u s c r i p t 6 brain abscess, always before neurosurgery, a procedure that could be delayed up to 6 weeks from diagnosis (mean delay 10.5 days; range 0-41 days).

For the purpose of the study, patients were divided into three groups: Group 1 comprised 12 patients who received CSC (cefotaxime + metronidazole); Group 2 comprised 22 patients who received i.v. imipenem 1 g/6-8 h; and Group 3 comprised 25 patients treated with i.v. meropenem 1 g/6-8h. No antiepileptic prophylactic therapy was administered prior to or simultaneously with the antibiotics. Treatments lasted a mean of 35.3 ± 16.3 days (range 16-84 days).

Pus from brain abscesses obtained by needle aspiration or surgical debridement in 43 patients was sent in capped syringes to the microbiology laboratory for Gram stain and aerobic and anaerobic cultures. Blood cultures were obtained from all the patients and CSF cultures from 15 patients.

Statistical analysis

Results

Patients

The characteristics of the patients in the three therapy groups are presented in Table 1. Carbapenems were used to treat brain abscesses after 2000 at HUCA and the annual incidence of the infection was fairly steady throughout the review period, therefore more than twice as many patients were treated with carbapenems than with CSC. In addition, owing to the non-randomised design of the study, patients in the CSC group were not well matched with those receiving carbapenems. In fact, patients receiving CSC were older, more often presented a Glasgow coma scale (GCS) score <7 and more often had multiple abscesses. Patients receiving the two carbapenems were acceptably well matched with regard to the clinical severity of the illness at hospital admission (GCS score, motor weakness, intracranial hypertension), although patients given imipenem were younger. All patients groups were well matched with regard to basic blood and serum determinations such as haemoglobin, total leukocyte count, differential count, platelet count, serum glucose, urea, creatinine and electrolytes (P = 0.1-0.9). All antibiotics were administered in a timely manner and at appropriate dosages.

A c c e p t e d M a n u s c r i p t 8

Number of brain abscesses

Abscesses were single in 42 patients (71.2%) and multiple in 17 patients (28.8%).

Microbiology and source of entry of the brain abscesses

Positive brain pus cultures were obtained in 27 (62.8%) of 43 cases, positive blood cultures in 15 (25.4%) of 59 cases and positive CSF cultures in 10 (66.7%) of 15 cases. Eleven patients had positive cultures from more than one source. A microbiological diagnosis was based on blood alone in 11 cases (18.6%) and on CSF alone in another 2 cases (3.4%). Anaerobes were isolated in 14 (23.7%) of 59 individuals and they were the most frequent isolates, followed by Gram-positive cocci (12/59; 20.3%), non-anaerobic Gram-negative rods (11/59; 18.6%) and mixed flora (3/59; 5.1%); in 19 patients (32.2%) no microorganisms were obtained from the brain pus or other cultures.

Many of the brain abscesses in this series were secondary to neurosurgical procedures (17/59; 28.8%) or head trauma (2/59; 3.4%), followed by those due to ear, nose and throat infections (14/ Patients remained in hospital on i.v. therapy for a mean of 36.5 ± 22.8 days (range 5-92 days). Overall, cure was achieved in 50/59 cases (84.7%), whereas 9 patients (15.3%) died, mostly due to cranial hypertension and other complications of brain abscess. Four of the patients who died did not undergo neurosurgery. A higher (not statistically significant) cure rate was observed in the carbapenem groups compared with CSC (89.4% of patients on carbapenems compared with 66.6% in the CSC group; P = 0.06). Comparing the two carbapenems, meropenem showed a non-significant slightly greater efficacy than imipenem (96.0% cured vs. 81.8%; P = 0.17). Meropenem was significantly more effective than CSC [24/25 patients (96.0%) receiving meropenem cured vs. 8/12 (66.7%) receiving CSC; 2 = 3.72, odds ratio (OR) = 12.0, 95% confidence interval (CI) 0.98-329.7; P = 0.03 by Fisher's exact test] (Table 1). Among the patients with multiple abscesses, seven received imipenem (one died; cure rate 85.7%), five received meropenem (all survived; cure rate 100%) and five received CSC (2 died; cure rate 60%) (P < 0.4 for all the comparisons).

Among the different epidemiological, bacteriological, clinical and surgical variables studied, only the GCS score was significantly associated with death (P = 0.001).

A c c e p t e d

M a n u s c r i p t 10

Neurosurgery

Neurosurgery was performed in 43/59 patients (72.9%); 17/22 (77.3%) on imipenem, 21/25 (84.0%) on meropenem and 5/12 (41.7%) on CSC (P = 0.02).

Sixteen patients did not undergo neurosurgery; 1/9 (11.1%) of those on carbapenems died and 3/7 (42.9 %) on CSC died (P = 0.26 comparing mortality rates of those who did not undergo neurosurgery in the two treatment groups).

Among the 43 patients who underwent neurosurgery, 20 (46.5%) underwent craniotomy and surgical drainage of the brain abscess, 17 (39.5%) underwent needle aspiration of the abscess through a burr hole and 6 (14.0%) had an Ommaya reservoir placed to relieve elevated intracranial hypertension.

Relapse

In total, 12 (20.3%) of the 59 patients relapsed requiring re-intervention; 7/22 (31.8%) on imipenem, 3/25 (12.0%) on meropenem (P = 0.1) and 2/12 (16.7%) on CSC (P < 0.5). The second surgical procedure was a new abscess puncture in all but three patients. Only four (33.3%) of the patients who underwent a second surgery had multiple abscesses.

Seizures

Seizures were observed only in those patients treated with carbapenems (10/47; 21.3%) and not in those on CSC (P = 0.1). There were significant differences when the three therapeutic groups were considered altogether (P =

Multivariate analysis

A Cox multivariate proportional hazard model was used to asses the independent association of different variables with death. The model included variables that were found to be related to patient survival on univariate analysis or that could be clinically relevant to this outcome, such as GCS score, antibiotic treatment and the presence or absence of cranial hypertension and surgical treatment. A GCS score <7 [hazard ratio (HR) = 26.3, 95% CI 2.2-333.3; P = 0.01) and treatment with cefotaxime + metronidazole (CSC) compared with meropenem (HR = 0.046, 95% CI 0.003-0.692; P = 0.026) were the only variables found to be significantly associated with death (Fig. 1), whereas imipenem treatment (P = 0.13), surgical treatment (P = 0.58) and cranial hypertension (P = 0.86) were not significantly related to this outcome.

Discussion

Carbapenem monotherapy proved to be an effective alternative to the standard combination of i.v. cefotaxime + metronidazole (CSC) when used in conjunction with neurosurgery to treat bacterial brain abscesses in this study. Meropenem Meropenem and imipenem penetrate into the CSF and show excellent antimicrobial activity in meningitis caused by different microorganisms [START_REF] Carton | Successful treatment of recurrent cerebral empyema and brain abscesses with imipenem[END_REF][START_REF] Meis | A brain abscess due to multiple-resistant Enterobacter cloacae successfully treated with meropenem[END_REF][START_REF] Asensi | Imipenem therapy of brain abscess[END_REF][START_REF] Modai | Penetration of imipenem and cilastatin into cerebrospinal fluid of patients with bacterial meningitis[END_REF][START_REF] Asensi | Therapy of brain abscess with imipenem-a safe therapeutic choice?[END_REF][START_REF] Baldwin | Meropenem: a review of its use in the treatment of serious bacterial infections[END_REF]. Imipenem has been shown to be present in high concentrations in brain pus and, although not reported so far, meropenem should behave similarly [START_REF] Modai | Penetration of imipenem and cilastatin into cerebrospinal fluid of patients with bacterial meningitis[END_REF][START_REF] Linden | Safety profile of meropenem: an updated review of over 6,000 patients treated with meropenem[END_REF][START_REF] Baldwin | Meropenem: a review of its use in the treatment of serious bacterial infections[END_REF]. Both drugs should be present at levels that are well above the minimum inhibitory concentration for 90% of microorganisms (MIC 90 ) for isolates from brain abscesses in this study, mostly obligate anaerobes and Grampositive cocci.

A c c e p t e d M a n u s c r i p t 13 Overall mortality in this study (15.3%) was similar to that reported in our previous work and in larger series [START_REF] Tseng | Brain abscess in 142 patients: factors influencing outcome and mortality[END_REF][START_REF] Asensi | Imipenem therapy of brain abscess[END_REF]. Jansson et al. [START_REF] Jansson | Efficacy and safety of cefotaxime in combination with metronidazole for empirical treatment of brain abscess in clinical practice: a retrospective study of 66 consecutive cases[END_REF] reported a much lower short-term abscess-related mortality (4.5%) and lower relapse rate (8.3%) with i.v. cefotaxime + metronidazole. However, they observed a 6-month mortality of 12%, similar to ours, and 60% of patients had adverse reactions, including a seizures rate at the end of therapy of 11%. No seizures were observed in our patients treated with i.v. cefotaxime + metronidazole at the same dose used by Jansson et al. [START_REF] Jansson | Efficacy and safety of cefotaxime in combination with metronidazole for empirical treatment of brain abscess in clinical practice: a retrospective study of 66 consecutive cases[END_REF].

Meropenem has been shown to be less epileptogenic than imipenem, with a seizure incidence as low as 0.07% in infections other than meningitis [START_REF] Baldwin | Meropenem: a review of its use in the treatment of serious bacterial infections[END_REF]. The convulsive activity of -lactams is related to inhibition of [ 3 H]-muscimol binding to the GABA A receptor in brain tissue. In vitro assays and clinical trials have shown that meropenem induced a much lower seizure activity than imipenem, although it was higher than other newer carbapenems such as doripenem and biapenem [START_REF] Day | Correlation between in vitro and in vivo models of proconvulsive activity with the carbapenem antibiotics, biapenem, imipenem/cilastatin and meropenem[END_REF][START_REF] Horiuchi | Absence of convulsive liability of doripenem, a new carbapenem antibiotic, in comparison with -lactam antibiotics[END_REF]. This study confirms the lower epileptogenic activity of meropenem compared with imipenem even in patients with a high risk of seizures such as brain abscesses with subsequent neurosurgery.

In many countries, i.v. metronidazole is not available and therefore meropenem could be an alternative. However, the cost of 5 weeks of i.v. therapy has to be considered by the clinician and hospital pharmacist because meropenem is the most expensive regimen (€5177 for i.v. meropenem, €4900 for i.v. imipenem and €1639 for the combination i.v. cefotaxime + metronidazole in Spain).

A c c e p t e d M a n u s c r i p t 14 We conclude that carbapenem monotherapy was more effective than CSC to treat brain abscesses, in addition to neurosurgery, and produced similar relapses. Meropenem, although the most expensive regimen, induced fewer seizures with slightly better clinical efficacy than imipenem and so may prove to be a better choice to treat this neurological infection.

Funding

None.

Competing interests

None declared.

Ethical approval

Not required. c Standard therapy versus imipenem (P = 0.4) and standard therapy versus meropenem (P = 0.03).

Edited Table 1

  author. Tel.: +34 98 510 8000 x38177; fax: +34 98 510 6158. E-mail address: vasensia@medynet.com (V. Asensi).  This work was presented in part at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), 25-28 October 2008, Washington, DC (poster #L-616).

  Qualitative variables were compared by2 or Fisher's exact tests as appropriate. The Gaussian distribution of continuous variables was tested with the Kolmogorov-Smirnov test, and the Student's t-test or Mann-Whitney U-test was used for comparison of these variables accordingly. One-way analysis of variance (ANOVA), with Scheffé post-hoc test, was used for comparison of more than two groups. The independent association of diverse variables with patient survival was assessed by a Cox proportional hazard model. A P-value A c c e p t e d M a n u s c r i p t 7 <0.05 value for a two-tailed test was considered statistically significant. SPSS v.15.0 software (SPSS Inc., Chicago, IL) was used for statistical analysis.

  ). However, if imipenem is compared with meropenem, the former induced significantly more seizures [8/22 (36.4%) for imipenem vs. 2/25 (8.0%) for meropenem; 2 = 4.05; OR = 6.57, 95% CI 1.04-52.8; P = 0.03 by Fisher's exact test]. No other important side effects of antibiotics were reported in the medical charts of patients.

A

  c c e p t e d M a n u s c r i p t 12 showed significantly greater efficacy in univariate analyses than CSC and was independently associated with a favourable outcome by Cox regression. Imipenem-treated patients had the highest incidence of seizures. These observations might make meropenem the best choice for empirical treatment of pyogenic brain abscesses. This is the largest study of carbapenems for the treatment of brain abscess ever published in the world literature. However, the non-randomised design of the study might have introduced a bias to the results and forces us to be very cautious in interpreting the results. Patients receiving CSC were older, had lower GCS scores, more often had multiple abscesses, less frequently underwent neurosurgery and were admitted before 2000. All these factors, alone or taken together, have been demonstrated to indicate a worse prognosis of brain abscesses in other studies and could work in favour of carbapenems.

A c c e p t e d M a n u s c r i p t 17 Fig. 1 .

 171 Fig. 1. Multivariate Cox regression curves to asses the association with death of

A c c e p t e d M a n u s c r i p t 1 1

 11 TableCharacteristics of patients with brain abscess in the three therapy groups CSC standard chemotherapy (cefotaxime+ metronidazole); S.D., standard deviation; GCS, Glasgow coma scale.a Standard therapy versus imipenem (P = 0.048) and standard therapy versus meropenem (P = 0.051), by Scheffé test.b Standard therapy versus imipenem (P = 0.06) and standard therapy versus meropenem (P = 0.018).

Edited Figure 1