Does presence of bone metastases portend worsened prognosis in metastatic renal cell carcinoma? Analysis of the REMARCC (Registry of MetAstatic RCC) database.

Abstract

655 Background: The presence of brain metastases and bone metastases are generally understood to herald worsened prognosis following nephrectomy in patients with renal cell carcinoma (RCC). However, we sought to determine the effect of bone metastases on outcomes when already present at the time of cytoreductive radical nephrectomy (RN). Methods: Multicenter retrospective analysis of mRCC patients from the REgistry of MetAstatic RCC) REMARCC. Demographics, clinical variables, and outcomes were collected. Patients were stratified into low, medium, and high-risk groups based on Motzer Criteria, and analysis of impact of bone metastases was conducted within each group utilizing Kaplan-Meier analysis (KMA). Multivariable analysis (MVA) was utilized to identify predictors for outcomes. Primary outcome was progression-free survival (PFS) and secondary outcome was overall survival (OS). Results: A total of 447 patients (low- n=30, intermediate- n=208, and high-risk mRCC n=123, median follow-up 14.3 months) were included in the analysis. 124 patients had bone metastases and 323 had mRCC but no bone metastases. No significant demographic differences were noted between groups. KMA (Figure) showed no difference in median PFS for bone metastases vs. non bone metastases groups (6.1 vs. 6.4 months, p=0.973). KMA showed no difference in median OS (25.5 vs. 26.5 months, p=0.958). Similarly, stratification of patients into different Motzer risk categories did not demonstrate difference between bone vs. none bone mRCC for PFS and OS. MVA for PFS demonstrated increasing Motzer risk category (low risk referent vs. intermediate OR 1.89, p=0.006, high risk OR 3.24, p<0.001) as independent predictors. MVA for OS revealed increasing Motzer risk category (low ref, vs. intermediate OR 1.88, p=0.033, high risk 5.17, p<0.001) as being predictive. In neither analysis was presence of bone metastases significant (PFS p=0.690, OS p=0.268). Conclusions: Presence of bone metastases does not independently predict survival or oncologic outcomes in mRCC. While further validation is needed, the prognostic significance of bone metastases may be less than previously thought.