SURGICAL TREATMENT OF RENAL CELL CANCER LIVER METASTASES; A POPULATION BASED STUDY Naam: Begeleider: Facultair begeleider: Instituut: Periode: Thony Ruys Prof. T.M. van Gulik Dr. A.J.M Karthaus Afdeling Chirurgie, AMC, Amsterdam, 06-07-2009 – 16-11-2009 ABSTRACT (English) INTRODUCTION Renal cell cancer (RCC) has an incidence of 1200 new patients in the Netherlands each year (12.5 per 100.000 inhabitants). Half of these patients ultimately develop metastases and prognosis of this group is poor with a 1-year survival of 10%. According to literature, the liver is involved in 20% of patients with metastatic RCC, however resection is feasible in only a minority (2-4%) of patients due to concomitant widespread disease. Hence, little is known about outcomes of surgical treatment in patients with resectable liver metastases of RCC . AIM To evaluate outcomes of surgical treatment in patients with hepatic metastases from RCC in the Netherlands and to identify prognostic factors for survival after resection. METHODS Patients were retrieved from local databases of the Netherlands Task Force for Liver Surgery (14 centres) and from the Dutch collective pathology database PALGA. From these national registries, 33 patients were identified who underwent resection n=(32) or local ablation (n=4) of hepatic metastases of RCC in the Netherlands, between 1990 and 2008. Patient and tumour characteristics, survival and prognostic factors in this specific patient population were analysed by Kaplan-Meier curves and logrank tests. RESULTS The overall 1-, 3- and 5-year survival rates were 78.6%, 45.1%, and 40.6%, respectively. Median survival was 26.6 months. There was no operative mortality and morbidity was 18%. At a median follow-up interval of 19.2 (3.45-188.9) months, 28 patients showed evidence of recurrence with a median time to recurrence of 10 (0.89-54) months. Metachronous metastases (n=23, p=0.04) and radical resection (n=24, p<0.001) were significant prognosticators of long-term survival. Size <50mm (n=18, p=0.84), solitary metastases (n=19, p=0.92) and surprisingly, presence of extrahepatic metastases (n=11, p=0.21) showed no significant influence on survival. CONCLUSION The survival rates and low operative morbidity and mortality found in this nation-wide study indicate that surgical treatment of patients with hepatic metastases of RCC can benefit from radical resection with 5-year survival rate of 40.6%. 2 ABSTRACT (Nederlands) INLEIDING Niercel carcinoom (NCC) heeft een incidentie van 1200 nieuwe patiënten in Nederland per jaar (12,5 per 100.000 inwoners). De helft van deze patiënten ontwikkelen uiteindelijk metastasen en de prognose van deze groep is zeer slecht met een 1-jaars overleving van 10%. Volgens de literatuur, is de lever betrokken bij 20% van de patiënten met gemetastaseerd niercelcarcinoom, resectie is echter slechts haalbaar bij een minderheid (2-4%) van de patiënten als gevolg van de vaak gelijktijdig wijdverbreide ziekte. Hierdoor is er weinig bekend over de resultaten van chirurgische behandeling bij patiënten met resectable levermetastasen van NCC. DOEL Evaluatie van de resultaten van chirurgische behandeling bij patiënten met levermetastasen van NCC in Nederland en het identificeren van prognostische factoren voor overleving na resectie. METHODEN Patiëntendata werd verzameld uit lokale databases van de werkgroep Leverchirurgie (14 centra) en van de Nederlandse collectieve pathologie database Palga. Uit deze nationale registers, werden 33 patiënten geïdentificeerd die resectie (n = 32) of lokale ablatie (n = 4) ondergingen van levermetastasen van NCC in Nederland, tussen 1990 en 2008. Patiënt en tumor kenmerken, overleving en prognostische factoren in deze specifieke patiëntenpopulatie werden geanalyseerd met behulp van Kaplan-Meier curves en logrank tests. RESULTATEN De algemene 1 -, 3 - en 5-jaars overleving was respectievelijk 78.6%, 45.1% en 40.6%. De mediane overleving was 26.6 maanden. Er was geen operatieve mortaliteit en morbiditeit was 18%. Bij een mediane follow-up interval van 19.2 (3.45-188.9) maanden, vertoonden 28 patiënten tekenen van recidief met een mediane tijd tot recidief van 10 (0.89-54) maanden. Metachrone metastasen (n = 23, p = 0.04) en radicale resectie (n = 24, p <0.001) waren significante prognostische markers voor lange termijn overleving. Grootte <50mm (n = 18, p = 0.84), solitaire metastasen (n = 19, p = 0.92) en verrassend genoeg, de aanwezigheid van extrahepatische metastasen (n = 11, p = 0.21) toonden geen significante invloed op de overleving. CONCLUSIE De overlevingskansen en lage operatieve morbiditeit en mortaliteit in dit landelijke onderzoek geven aan dat chirurgische behandeling aan patiënten met levermetastasen van RCC een voordeel kan bieden, met een 5-jaarsoverleving van 40.6% 3 TABLE OF CONTENTS ABSTRACT (English) ........................................................................................................... 2 ABSTRACT (Nederlands) ..................................................................................................... 3 INTRODUCTION .................................................................................................................. 5 MATERIALS AND METHODS ........................................................................................... 8 Patients ............................................................................................................................... 8 Primary tumour .................................................................................................................. 9 Metastases .......................................................................................................................... 9 Statistical Analysis ............................................................................................................. 9 RESULTS............................................................................................................................. 11 Operative data .................................................................................................................. 11 Survival ............................................................................................................................ 11 Disease-free survival ........................................................................................................ 12 Univariate analysis of prognostic factors ......................................................................... 12 DISCUSSION ...................................................................................................................... 14 Appendix A .......................................................................................................................... 21 Appendix B .......................................................................................................................... 22 4 INTRODUCTION Renal cancer is the 7th leading malignant condition among men and the 12th among women, accounting for 2.6 percent of all cancers worldwide1. In the Netherlands 1200 people are diagnosed with RCC each year. The incidence of RCC in the Netherlands is 12,5 per 100.000 inhabitants and is gradually rising due to the sharp rise in the ageing population. The classic presentation of renal-cell carcinoma (RCC) includes the triad of flank pain, hematuria and a palpable abdominal mass, however only 10% of patients present with these classic symptoms. Most patients are identified because a renal mass is incidentally detected on radiographic examination2. Ultrasound (US), chest radiography, computed tomography (CT) and magnetic resonance imaging (MRI) are used for primary diagnosis and staging3. Surgical excision is still the primary treatment for renal cell carcinoma. The surgical approach is determined by the size and location of the tumor within the kidney and the TNM stage. Total ‘en bloc’ nephrectomy used to be the gold standard, however nowadays this is no longer the case for small tumors (less than 7 cm)4. In patients with small tumors, bilateral tumors and bad kidney function a partial nephrectomy is currently considered as the appropriate treatment5. In this selection of patients cryoablation of the tumour has also shown promising results, however randomised controlled trials confirming these results are lacking6. In addition, laparoscopic surgery has also been explored and shown good results7. 5-Years survival can be predicted by the TNM staging system and varies from 95% in T1 tumors to 20% in T4 tumors8 (figure 1). Figure 1. TNM staging RCC; Cohen HT, McGovern FJ. Renal-cell carcinoma. N Engl J Med 2005; 353:2477-2490. 5 RCC is relatively little affected by radiotherapy9. Rates of response to chemotherapy alone are very low and have not proven effective as an adjuvant therapy10. The immune responsiveness of renal-cell carcinoma could possibly provide an opportunity for the development and optimization of immune therapies1. Several immunomodulatory therapies are currently under research including interferon alpha and interleukin-2, however multiple randomised trials haven’t demonstrated any benefit11,12. Recently molecularly targeted therapy has become available for advanced renal cell carcinoma and has until now shown promising results. Sunitinib and sorafenib, two small molecule tyrosine kinase inhibitors allowing the blocking of the vascular endothelial growth factor (VEGF) pathway, both showed overall survival benefit in big multicentre trials13,14. At presentation 25 to 30% of patients have distant metastases and another third of patients develop metastatic recurrence after primary tumour resection15. The lung is most frequently involved in patients with RCC, namely in 50-60% of patients with metastatic disease16. Liver metastases develop in 30%–40% of patients with metastatic disease. Prognosis is poor in patients with metastatic RCC, only 10% survive more than a year17. The development of hepatic metastases is generally considered a poor prognostic factor and a frequent predictor of more widespread disease18. Only 2% to 4% of patients have isolated metastases and are candidates for radical surgery19. As a result, numbers of hepatic resections for RCC are small for individual centres, complicating clinical studies in these patients. Liver surgery for colorectal metastases has evolved over the last decades. When mortality rates for liver surgery started to drop in the late 70’s, the indication for a liver resection widened20. As a result, the once incurable patient with colorectal metastases to the liver obtained a possibility of long-term survival. Over the following years large series have arisen in literature describing a 5-year survival after resection of over 30% in highly selected patient groups. Today, 5-year survival rates have been improved even more. For instance, Pawlik et al recently reported a series with a 5-year survival of 47,3% in 1669 patients treated surgically (resection +/- radiofrequency ablation) for colorectal liver metastasis. In addition, the indication for treatment of hepatic metastases widened due to the development of new techniques as portal vein embolisation21, RFA22, two-stage hepatectomy23, downsizing of metastases with neoadjuvant chemotherapy24 and new systemic therapies25. In contrast with the immense amount of studies and reports about surgical outcomes of colorectal liver metastases, relatively little is known about surgical outcomes of hepatic metastases originating from other organs. One valid argument for this phenomenon is the high incidence of colorectal liver metastases in comparison with hepatic metastases from other origin. Nevertheless, the lack of high-level evidence (i.e. prospective randomised clinical trials) for surgical treatment of non-colorectal hepatic metastases is still remarkable. Data about surgical outcomes of hepatic metastases originating from organs other than the colon are often pooled in series with non-colorectal metastases. Due to the recognition that patients with endocrine metastases are a unique group with a better prognosis, a subclassification of patients with non-colorectal non-endocrine tumours was formed. These include metastases from genitourinary malignancies, sarcomas, breast cancer, melanoma and other primary tumors. Tumour biology and clinical behaviour varies substantially among all these different malignancies. Consequently, unfortunately, analysis of survival following surgical treatment in this group of patients still suffers from a large heterogeneity of primary tumours and limited numbers of patients. Adam et al recently reported the first large series (more than 150 patients) about the outcomes of hepatic resection in 1452 patients with noncolorectal non-endocrine metastases. Five-year survival rates in this study varied from 8% in 6 patients with primary lung carcinoma to 66% in patients with a primary tumour in an adrenal gland. Hence, this illustrates the complexity of interpreting results from hepatic resection in the heterogeneous group of patients with non-colorectal non-endocrine liver metastases. In most studies published, patients with metastatic RCC to the liver are part of a larger group of patients with liver metastases from non-colorectal and non-neuroendocrine tumors26. Furthermore, RCC itself is characterized by large heterogeneity in clinical course (from highly progressive to indolent and even regression), disease-free interval (synchronous to more than 20 years from primary treatment) and pattern of dissemination (including rare localisations i.e. pancreas, skin, muscle, thyroid). Although relatively few patients (2-4% as described above) present with a metastatic disease that is potentially curable by radical resection, long-term survival following hepatic resection is described in literature. Adam et al reviewed the literature and identified 15 reports with combined survival data of 64 patients with hepatic resections for RCC metastases18. In this combined series 2-year mortality was 40%, which is substantially higher than 10% survival after one year in patients with unresected renal cell metastases17,27. Therefore, Adam et al concluded that liver resection should be offered to all these patients if a complete radical resection is feasible. The objective of this study was to determine patient and tumour characteristics, survival and prognostic factors in patients with hepatic metastases from RCC in the Netherlands. This will provide a better insight in several aspects of hepatic RCC metastases and will probably help us in better selection of patients for surgery or local ablative techniques. In addition, identification of patients at high risk of recurrence may guide adjuvant therapy using novel systemic agents like sunitinib or sorafinib in the future. 7 MATERIALS AND METHODS Patients For study data acquisition two methods were used. This study was conducted under the direction of the Netherlands Liver Task Force and all members were sent a letter (appendix A). In this letter the members were asked to check their local databases if they had surgically treated patients with hepatic metastases from RCC in the past. A specific questionnaire designed to acquire a variety of patient, primary tumor, metastases, treatment and outcome variables was attached to this letter. In addition, one of the investigators (ATR), visited a part of the hospitals to acquire the data. In order to identify a complete cohort of patients with hepatic metastases from RCC treated surgically in the Netherlands a second method was used, a search in the nationwide histopathology database PALGA was performed28. PALGA (‘Pathologisch Anatomisch Landelijk Geautomatiseerd Archief’; Pathological Anatomy National Automated Archive) is a nationwide network and archive that has been setup in the Netherlands in order to facilitate the optimal use of histopathology and cytopathology data. PALGA has been available since 1971. The PALGA system is a highly automated pathology archiving and communication tool that provides support to pathologists in their daily practices. As a result, the PALGA network was joined by all 64 histopathology and cytopathology laboratories in The Netherlands. A continuously expanding automated archive of excerpts of pathology reports with currently about 42 million excerpts on nearly 10 million patients in the central databank was created28. The patient information obtained by the search in the PALGA database was used to contact the hospitals concerned and additional data was acquired by sending the previously described questionnaire. Survival data were obtained from the local hospitals and updated, if necessary, by contacting the primary care physicians. Twenty patients were identified by the questionnaire, which was send to the members of the Netherlands Liver Task Force. An additional seventeen patients were identified by the search in the PALGA database28. The data from four of these patients could not be retrieved, as a result of unavailability of the data in the hospitals concerned presumably as a consequence of the long time period between treatment and retrieval of the data. The data of an additional thirteen patients could be retrieved by the search in the PALGA database, resulting in a study population of 33 patients (16 men, 17 women) with hepatic metastases from RCC, who were surgically treated in the Netherlands. The median age was 61 (range 20-77) years. Data was obtained from a total of 14 hospitals, including 7 academic and 7 referring hospitals (appendix B). Patients with direct ingrowth of the primary tumour in the liver or ingrowth of peritoneal metastases in the liver were excluded from this analysis because of expected different tumour biology. Patients with nephroblastoma as primary tumour were excluded from this analysis as well, because these patients have a much worse outcome18. 8 Primary tumour Histopathology of the primary tumour could be retrieved in 28 (84%) patients and showed clearcell-carcinoma in 21 (63%) patients, chromophobic carcinoma in 3 patients (9%), papillar carcinoma in 3 patients (9%) and another type in 2 patients (6%). Primary tumour site was the left kidney in 14 (42%) patients, the right kidney in 17 (52%) patients, bilateral in 1 (3%) patient and unknown in 1 (3%) patient. TNM staging at the time of primary tumour removal of the primary tumour was unknown in 12 patients (36%), T1 in 1 patients (3%), T2 in 3 patients (9%), T3 in 7 patients (21%) and T4 in 11 patients (33%). Lymph node status was unknown in 14 patients (42%), node negative (N0) in 17 patients (51%) and node positive (N1) in 3 patients (9%). Distant metastases were present (M1) in 12 patients (36%), absent (M0) in 10 patients (30%) and unknown in 11 patients (33%). Metastases Liver metastases were synchronous in 10 patients (30%), whereas 23 patients (70%) had metachronous metastases. The median interval of metachronous metastases between nephrectomy and diagnosis of liver metastases was 50 (range: 7-360) months. Liver metastases were symptomatic in 11 patients (33%), asymptomatic in 9 patients (27%) and unknown in 13 patients (39%). Symptoms described included: abdominal pain, a palpable mass, malaise, fatigue and losing weight. Liver metastases in asymptomatic patients were discovered by routine ultrasound or computed tomography for different reasons. Liver metastases were solitary in 19 patients (57%) and multiple in 14 patients (43%). The median number of metastases was 1 (range: 1-19). Median size of the hepatic metastases was 42 (range 3-150) millimetres. Metastases were localised in the left lobe of the liver in 10 patients (33%), in the right lobe of the liver in 20 patients (60%), in both lobes of the liver in 2 patients (6%) and the localisation was not reported in 1 patient (3%). At the time of diagnosis of the liver metastases there was evidence of extrahepatic disease in 11 patients. These extrahepatic metastases included metastases to vagina, omentum, bile duct, diaphragm, adrenal gland, gall bladder and lung. The patient with metastases to the bile duct was previously described in the literature29. Statistical Analysis Data were analyzed using the SPSS software program. Survival was evaluated according to the method of Kaplan and Meier. Prognostic variables related to the patient (sex and age), primary tumour (side), hepatic metastases (number, size, metachronous or synchronous and time between metastases and primary tumour), presence of extrahepatic disease and radicality of resection were evaluated with regard to patient survival. Groups were compared by univariate analysis with the log-rank test. The univariate tested variables tested were chosen based on described variables from prior reports in metastatic renal cell carcinoma and studies on colorectal liver metastases. A multivariate analysis was not feasible in this study, due to the small sample size. P values of <0.05 were considered as statistically significant. 9 Table I: Patient and tumour characteristics of patients with hepatic metastases from renal cell carcinoma. Factor Number of patients (N=33) Sex Male 16 Female 17 Age Median (range) 61 (20-77) Primary tumour Side Left 14 Right 17 Bilateral 1 T T1-T2 4 T3 7 T4 11 N N0 17 N1 3 M M0 10 M1 13 Histology Clearcell 21 Chromofobic 3 Papillary 3 Other / Unknown 6 Metastases Time Synchronous 10 Metachronous (interval range) 23 (7-360 months) Symptomatic Yes 9 No 11 Size ≤50mm 18 >50mm 12 Number Solitary 19 Multiple (interval range) 14 (2-19) Localisation Left liver lobe 10 Right liver lobe 20 Bilateral lobes 2 Extrahepatic disease Yes 11 No 22 Missing numbers are a result of unknown data. % 48 52 44 53 3 18 32 50 85 15 43 57 64 9 9 18 30 70 45 55 60 40 58 42 32 62 6 33 67 10 RESULTS Operative data The surgical treatment performed in these patients included 8 metastasectomies (24%), 10 segmentectomies (30%), 4 left hemihepatectomies (12%), 6 right hemihepatectomies (18%), one extended right hemihepatectomy and 4 radio frequency ablations (RFA). In 3 patients RFA was performed in addition to a resection and in one patient RFA was the only treatment. Resection of the metastases was margin negative in 24 patients (73%), as defined by removal of all macroscopically detectable disease and microscopically clear resection margins or adequate successful ablation in the case of RFA. All RFA procedures were performed after laparotomy. 12 Patients received additional systemic treatment including chemotherapy, immunotherapy (IFN and IL-2) and molecularly targeted therapy (sunitinib and sorafenib). There was no operative mortality and postoperative complications developed in 6 patients (18%). This operative morbidity included lung embolism in atrial fibrillation, haemorrhage, reversible liver failure, pleural fluid and an intra-abdominal abscess. Re-intervention was required in one patient as a result of intra-abdominal haemorrhage. Survival Complete survival data could be retrieved from all but three patients (9%), who were lost to follow-up. At the end of the study seventeen patients (52%) had died. Of the sixteen patients (48%) alive, 11 patients had evidence of recurrent disease (recurrence of liver metastases or extrahepatic disease). Overall 1-, 3- and 5-year survival rates were 78.6%, 45.1%, and 40,6%, respectively (Figure 2). The median survival was 26,6 (3,5-199) months. Figure 2. Overall survival and disease-free survival of surgical treatment in patients with hepatic metastases from RCC. 11 As described above, 24 patients had free surgical margins (R0-resection). The 1-year, 3year and 5-year survival rates of patients with a radical resection were 91,5%, 61,9% and 55,7% respectively. These rates contrast sharply with the survival rates of patients with non-radical resection (R1), namely 44% 1-year survival and zero 3-year and 5-year survival. Disease-free survival The time to recurrence of disease, defined as recurrence of liver metastases or evidence of extrahepatic disease, ranged from 0,89 to 54 months with a median of 10 months. The 1year, 3-year and 5-year disease-free survival (DFS) rates were 48,5%, 17,4% and 10,4% respectively (Figure 2). None of the patients Figure 3. Overall survival according with recurrent hepatic metastases underwent to resection margins (p=0.001) repeat hemi-hepatectomy or other additional treatment for hepatic recurrence. Median survival of patients with recurrent disease was 18,5 (3,45-198,9) months. One patient was diagnosed with metastases to the lungs after 33 months. He survived two consecutive metastasectomies of the lungs and is still alive after 199 months. Figure 4. Overall survival according to the presence of extrahepatic disease (p=0,21) and timing of metastases (p=0.04). Univariate analysis of prognostic factors In the univariate analysis two factors showed statistically significant influence on survival. As described earlier, resection margins had a tremendous effect on outcome. None of the patients with an irradical resection survived longer than 23 months, in contrast with patients with a 12 radical resection, who had a median survival of 83,9 months. This difference was highly significant (P<0.0001). Patients with synchronous metastases had a significantly (P=0,04) shorter survival (median survival of 17,3 months) than people with metachronous metastases (median survival of 83,9 months). This effect slightly diminished when we compared the patients with a disease-free survival of less than 24 months with more than 24 months between primary tumour and hepatic metastases. The median survival of patients with a disease-free survival of less than 24 months after the primary tumour (this obviously included the synchronous metastases) was 22,1 months. Patients with a disease-free survival of more than 24 months had a median survival of 83,9 months. This effect was not significant (p=0,08). Age (patient ≤ 60 years of age versus > 60 years of age), sex and the side of primary tumour had no significant influence on survival. Number of metastases and the size of the largest metastasis had no significant influence on survival (table II). To our surprise patients with extrahepatic disease had a longer median survival (median survival of 60 months) compared to patients with no extrahepatic metastases (median survival of 26,6), although this was not significant (P=0,213). The results of the univariate analysis are depicted in table II. Table II. Univariate analysis of prognostic variables in patients with hepatic metastases from renal cell carcinoma. Nr of Patients Median Survival (Months) P value Age ≤ 60 yr 16 26,6 0,26 > 60 yr 17 Sex Male 16 26,6 0,38 Female 17 33,3 Primary tumour side Left 14 33,3 0,95 Right 17 26,6 Liver metastases Timing Synchronous 10 17,3 0,04 * Metachronous 23 83,9 Disease-free interval ≤ 24 months 17 22,13 0,084 > 24 months 16 83,9 Size of largest metastasis ≤ 50 mm 18 33,3 0,84 > 50 mm 12 24,4 Number of metastases Solitary 19 26,6 0,90 Multiple 14 33,3 Extrahepatic disease Present 22 26,6 0,21 Absent 11 60,0 Resection margin Radical resection (R0) 24 83,9 <0,001 * Irradical resection (R1/R2) 9 9,2 13 DISCUSSION Despite improvements in surgery and systemic therapy in the last decades the prognosis of patients with metastasized renal cell carcinoma is still poor. Conventional systemic therapies like chemotherapy, radiotherapy have shown little to no influence on survival in these patients. Albeit, molecularly targeted therapy has shown hopeful results. Nevertheless, even though these drugs give significant survival benefit, they do not provide possibility on long-term survival. The lungs are most commonly affected in metastatic RCC, namely in 50-60% of patients with metastastic disease. The outcomes of surgery on RCC metastases to the lungs have been quite well investigated. Several relatively large series, although retrospective and non-randomised, emphasize survival benefit and possibility on long-term survival (up to 37% 5-year survival rate30) after radical resection in selected patients with relatively few complications30-32. Factors correlating with good prognosis found in these studies included solitary lesions, metachronous presentation, greater disease-free interval and radical resection. Liver metastases are less common in patients with metastatic RCC, but still occur in roughly 20% of patients with metastatic RCC. Patients with RCC metastases to the liver have a particularly poor prognosis, which is even worse than patients with RCC metastases to other organs, like lungs and bone33. In a series of Suppiah et al33, the median survival of 186 untreated patients with hepatic RCC metastases was only 7,8 months. Data about the efficacy of surgical treatment in hepatic RCC metastases are still very rarely reported. In addition to the fifteen reports reviewed by Aloia et al18, describing survival data of 64 patients, two studies were published26,34. Thelen et al34 described their single institution experience in 31 patients who underwent hepatic resection for RCC metastases. The overall 1-, 3- and 5-year survival rates reported in this study were 82.2%, 54.3%, and 38.9%, respectively. As mentioned earlier Adam et al26 described a series of 1452 patients with noncolorectal non-endocrine hepatic metastases. In this series 85 patients were enrolled with a primary RCC. Overall median survival and 5-year survival rates reported in this study were 36 months and 38% respectively. The present study had zero operative mortality and complication only occurred in 18% of the patients. An explanation for this low operative mortality and morbidity is that a large proportion of the resections were minor resections (metastasectomies and segmentectomies) and only 48% of patients underwent a hemihepatectomy. The reported survival rates in this study are superior to the results of older series reviewed by Alioa et al and comparable to the recently published series from Adam and Thelen18,26,34. As Thelen mentioned as well about their own series, the improved survival rate of our study could well be explained by: advancements in imaging technology resulting in more adequate staging and assessment of disease extend; better appreciation of tumour and patient characteristics that influence prognosis resulting in an improved patient selection; improvements in surgical technique including local ablative techniques and perioperative care resulting in a safer approach to large resections. 14 We contacted all centres performing liver surgery in the Netherlands. Furthermore we did a search in the nationwide histopathology database PALGA, in which all data about resection specimens in the Netherlands is stored. By doing so we believe that we retrieved nearly all patients who underwent surgical treatment for hepatic metastases from RCC in the last 19 years in the Netherlands. This fact addresses another interesting point Figure5. Incidence and mortality of RCC in the of this study. The number of new Netherland in the period 1989-2003. Source: Nederlandse patients diagnosed with RCC in the kankerregistratie, http://cijfers.ikcnet.nl ). Netherlands has been quite stable over the last years around 1200 (figure 5). Because we know that approximately 10% of patient with RCC ultimately develop liver metastases16, we can make a rough estimation of the total patients with liver metastases from RCC and the percentage who were surgically treated in this time period in the Netherlands. In the last 19 years roughly 2280 (10% of 19x1200) patients were diagnosed with hepatic metastases from RCC. In this particular time period we identified 33 patients who where surgically treated, which signifies that approximately 1,5% of the patients received surgical intervention. This number is in accordance with the percentage described by Dineen et al19. This emphasises once more the remarkably small proportion of these patients who are treated surgically. Previous studies reported prognostic factors influencing survival aiming to establish selection criteria for resection. Prognostic factors predicting long survival described in previous series included male gender, a maximum metastasis diameter ≤ 5 cm, left primary tumour localisation, disease-free interval >24 months, and margin negative resection margins. In our series only metachronous metastases and radical resection had a positive impact on survival rates in univariate analysis. To our surprise, patients with extrahepatic disease had a better survival than patients with only hepatic metastases, although this was not significant. The conclusion that extrahepatic disease improves survival would be ridiculous. Nonetheless in our opinion these results strongly suggest that extrahepatic disease has no significant influence on survival, which is in concordance with data from Alioa et al18. We assume that hepatic metastases strongly dictate the survival rate above metastases to other organs. In other words, these patients die from hepatic metastases before metastases to other organs start to influence survival. This assumption would have huge impact on management in this particular patient group, because this would implicate that potentially resectable extrahepatic disease is not a contraindication for liver surgery. On the other hand, we realize that our data has limited power to draw these strong conclusions. Our study certainly has limitations. Data were obtained from a complete, but relatively small group of patients, resulting in the impossibility of performing an adequate multivariate analysis. Data was retrieved from a long study period (eighteen years), in which as described before, many improved techniques in imaging, perioperative care and liver surgery were introduced. Only an extremely small selection of patients, that is the patients eligible for resection, was enrolled in the study resulting in an obvious selection bias. Data was retrospectively retrieved resulting in the well-known problems of retrospectively obtained 15 data: incomplete data, selection bias and improved possibility of confounding factors. And finally, data was retrieved from fourteen hospitals, including seven referral and seven academic hospitals, all with different selection criteria. Hence, care must be taken in drawing strong conclusions with the available data. The survival-rates presented in this study and results from previous studies18,26,34 are well comparable to results of hepatic resection for colorectal metastases. Survival rates are also certainly not inferior to results after resection of pulmonal metastases in patients with RCC. Please note that an aggressive surgical approach to these pulmonary metastases, in which a radical resection can be reached, is currently considered as the appropriate treatment. The future will tell us whether surgical treatment for hepatic RCC metastases will follow the path of treatment for colorectal liver metastases, which started with small retrospective series in highly selected patients in the seventies and advanced at present to a standard treatment in a large portion of patients justified by large randomised controlled trials. The result of this study in any case supports a much wider indication for liver resection in patients with RCC and denies the suggestion that patients with hepatic metastases from RCC cannot be cured. Future research should further define the role of sunitinib and sorafenib as (neo)adjuvant therapy. In conclusion, surgical treatment for hepatic metastases from RCC is only performed in roughly 1,5% of patients. Data from this study, in accordance with data from almost 150 patients reported in literature suggest that surgical treatment can provide reasonable survival rates, with a 5-year survival of 40%. The data available today combined with the unavailability of effective systemic therapy justifies an aggressive surgical approach in patients with hepatic metastases from RCC when margin negative resection can be obtained. In addition, our data suggests that extrahepatic disease is not a contraindication for surgical intervention when radical resection of all tumor sites is feasible. Prognostic factors influencing survival in literature are contradictory, with the exception of margin negative resection, which is a prognosticator for long-term survival in all studies. Further research is warranted and may provide selection criteria for these patients. 16 References 1. Cohen HT, McGovern FJ. Renal-cell carcinoma. N Engl J Med 2005; 353:2477-2490. 2. Russo P. Localized renal cell carcinoma. 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Academisch Medisch Centrum, Amsterdam VU Medisch Centrum, Amsterdam Nederlands Kanker Instituut-Antoni van Leeuwenhoek Ziekenhuis, Amsterdam Universitair Medisch Centrum St Radboud, Nijmegen Erasmus Medisch Centrum -Daniel den Hoed Kanker Centrum, Rotterdam Universitair Medisch Centrum Groningen, Groningen Universitair Medisch Centrum Utrecht, Utrecht Maastricht Universitair Medisch Centrum, Maastricht Deventer Ziekenhuis, Deventer Isala klinieken, Zwolle Leids Universitair Medisch Centrum, Leiden Amphia Ziekenhuis, Breda Maxima Medisch Centrum, Eindhoven Gelre Ziekenhuizen, Apeldoorn Medisch Centrum Haaglanden, Den Haag Medisch Spectrum Twente, Enschede 21 Appendix B Hospitals participating in this study: Academisch Medisch Centrum, Amsterdam VU Medisch Centrum, Amsterdam Nederlands Kanker Instituut-Antoni van Leeuwenhoek Ziekenhuis, Amsterdam Universitair Medisch Centrum St Radboud, Nijmegen Erasmus Medisch Centrum -Daniel den Hoed Kanker Centrum, Rotterdam Universitair Medisch Centrum Groningen, Groningen Maastricht Universitair Medisch Centrum, Maastricht Leids Universitair Medisch Centrum, Leiden Amphia Ziekenhuis, Breda Maasland Ziekenhuis, Sittard Maxima Medisch Centrum, Eindhoven Gelre Ziekenhuizen, Apeldoorn Medisch Centrum Haaglanden, Den Haag Medisch Spectrum Twente, Enschede 22