Do patients receiving whole-brain radiotherapy for brain metastases from renal cell carcinoma benefit from escalation of the radiation dose?

Purpose: Whole-brain radiotherapy (WBRT) is the most common treatment for brain metastases from renal cell carcinoma (RCC). Most patients cannot receive more aggressive therapies including surgery or radiosurgery. The standard WBRT regimen, 30 Gy/10 fractions (10 × 3 Gy), has resulted in poor survival (OS). This study investigates whether escalation of the WBRT dose improves treatment outcomes. Methods and Materials: Data from 60 patients receiving WBRT for brain metastases from RCC were retrospectively analyzed. A dose of 10 × 3 Gy (n = 31) was compared with higher doses (40 Gy/20 fractions or 45 Gy/15 fractions; n = 29) for OS and local control (LC). Additional factors evaluated were patient age, sex, performance status, number of metastases, interval from diagnosis of RCC to WBRT, extracerebral metastases, recursive partitioning analysis (RPA) class, and year of WBRT. Results: The OS at 6 months was 29% after 10 × 3 Gy and 52% after higher doses (p = 0.003). The OS at 12 months was 13% and 47%, respectively. On multivariate analysis, higher WBRT doses (p = 0.022), Karnofsky performance status score ≥70 (p = 0.017), fewer than four brain metastases (p = 0.035), and RPA Class 1 (p = 0.003) resulted in better OS. The LC at 6 months was 21% after 10 × 3 Gy and 57% after higher doses (p = 0.013). The LC at 12 months was 7% and 35%, respectively. On multivariate analysis, fewer than four brain metastases (p < 0.001) were associated with LC. A trend was found for WBRT regimen (p = 0.06) and RPA class (p = 0.06). Conclusions: The findings suggest that escalation of the WBRT dose beyond 10 × 3 Gy improves outcomes in patients with brain metastases from RCC. The results should be confirmed in a randomized trial stratifying for significant prognostic factors.