Prognostic significance of intensive local therapy to bone lesions in renal cell carcinoma patients with bone metastasis

We evaluated the prognostic roles of local therapy to bone metastasis (BM) in metastatic renal cell carcinoma (mRCC) patients with BM. This retrospective study included 71 mRCC patients with BM. Local therapy to BM included en bloc resection, curettage, and radiotherapy (RT). RT was classified into RT with biological effective dose (BED) ≥85 Gy and <85 Gy by its therapeutic intensity. Local therapy to BM was given for 64 patients (90 %): en bloc resection, curettage, and RT for 16, 10, and 38 patients, respectively. Fifteen patients received RT with BED ≥85 Gy. The median overall survival (OS) was 25 months (median follow-up 16 months). For 46 patients with solitary BM, patients treated with en bloc resection, curettage, and RT with BED ≥85 Gy showed significantly better OS than those treated with RT with BED <85 Gy or no local therapy (P = 0.006). Because OS was comparable among patients treated with en bloc resection, curettage, and RT with BED ≥85 Gy, these three treatment modalities were defined as “intensive local therapy”. Intensive local therapy to BM was also associated with favorable OS with marginal significance (P = 0.052) in a cohort of 25 patients with multiple BM. A multivariate analysis in the whole cohort revealed that intensive local therapy to BM was independently associated with favorable OS (hazard ratio 0.23, P < 0.001) along with Memorial-Sloan Kettering Cancer Center risk category (P < 0.001). Thus, intensive local therapy to BM might improve OS in mRCC patients with BM including multiple BM.