Prognostic Impact of Bone Metastasis on Survival Outcomes in Patients with Metastatic Renal Cell Carcinoma Treated by First Line Tyrosine Kinase Inhibitors: A Propensity-Score Matching Analysis

Purpose: To investigate the effect of bone metastasis (BM) on survival outcomes in patients with metastatic renal cell carcinoma (mRCC) treated with first-line tyrosine kinase inhibitors (TKI) by performing propensity-score matching (PSM) analysis. Materials & Methods: We retrospectively reviewed 1,151 patients with mRCC who were treated with first-line TKI from December 2006 to September 2016. After excluding 135 patients, 1,016 patients with mRCC were finally analyzed. The primary and secondary end points were overall survival (OS) and progression-free survival (PFS), respectively. After 1:1 PSM analysis, survival outcomes were compared between patients with BM (n=237) and without BM (n=237). Multivariate Cox regression analysis was used to determine predictors of survival. Results: Among 1,016 total patients, 27.5% (n=279) had BM. Before PSM, patients with BM had worse OS outcomes than those without BM. Even after PSM, OS was significantly poorer in patients with BM compared to those without BM. Of note, the presence of BM was identified as an independent predictor of OS (HR=1.36), in addition to prior nephrectomy, sarcomatoid differentiation, and IMDC risk group. However, there were no differences in PFS according to the presence of BM after PSM. In the subgroup analysis, only intermediate IMDC risk group showed significant differences in OS according to the presence of BM. Conclusion: Based on PSM analysis, the presence of BM negatively affected OS outcomes in patients with mRCC treated with first-line TKI, particularly in the IMDC intermediate risk group.