463 Background: Bone metastases (BMs) are associated with significant morbidity and shorter survival in metastatic renal cell carcinoma (mRCC). Our purpose was to identify prognostic factors for mRCC patients (pts) with BMs. Methods: Data from mRCC pts with BMs, treated at Gustave Roussy between April 1992 and March 2016, were retrospectively collected. Age, sex, ECOG-Performance Status (PS), Memorial Sloan-Kettering Cancer Center (MSKCC) score, histology, number and site of BMs, concomitant metastases (presence and sites), therapy for BMs (radical resection or palliative surgery, radiotherapy, other local and systemic treatments), time to BMs, and outcome were analyzed. Synchronous solitary bone metastasis (SSBM) was defined as a single bone metastasis without concomitant visceral lesions at the initial diagnosis of RCC. Overall survival (OS) was calculated from the date of BMs diagnosis to death or last follow-up using Kaplan-Maier method and modelled with Cox-regression analysis. Results: Three hundred pts were identified. Median time to BMs was 32.4 months (range 0–324 months). In 64 pts (21%), bone was the only metastatic site and 22 of them (7%) had a SSBM; 236 pts (79%) had concomitant metastases in other sites. Median OS was 23.22 months. SSBM pts had better OS then those with concomitant metastases (40 vs. 20 months; p<0.001). At univariate analysis, number of BMs (p<0.0001), spinal column as site of BMs (p<0.005), concomitant metastases (p<0.0001), Fuhrman grade (p<0.001), non-clear cell histology (p<0.003), and MSKCC score (p<0.001) were significantly associated with poor prognosis. At multivariate analysis, concomitant metastases remained predictor of poor prognosis while good MSKCC, radical resection, and SSBM were predictors of better OS. Conclusions: To our knowledge,this is the largest single-institution experience evaluating prognosis in pts with BMs from RCC. This study suggests that MSKCC score, number of BMs (1 vs. >1) and radical resection are prognostic factors. Additionally, in presence of solitary bone metastasis without other concomitant metastases at the initial diagnosis of RCC, bone surgery should be considered to achieve local tumor control and increase survival.
GPNMB overexpression is associated with extensive bone metastasis and poor prognosis in renal cell carcinoma
