Preliminary clinical observation of efficacy and safety of stereotactic body radiation therapy in combination with targeted therapy for metastatic renal cell carcinoma

Objective To evaluate the preliminary clinical efficacy and safety of stereotactic body radiation therapy (SBRT) in combination with targeted therapy for metastatic renal cell carcinoma (mRCC). Methods Clinical data of 58 patients with mRCC who were treated with SBRT in combination with targeted therapy in Sun Yat-sen University Cancer Center from June 2013 to December 2018 were retrospectively analyzed. Among them, 79.3% patients were classified as intermediate or high risk according to International Metastatic Renal Cell Carcinoma Database Consortium Criteria. The median biologically equivalent dose (BED) was 147 Gy (67 to 238 Gy). Results Overall, 32, 13, 7, 5 and 1 patients received SBRT for 1, 2, 3, 4 and 6 metastatic sites (105 lesions) and 71.4% of them were bone lesions. Targeted therapy was continued during SBRT. With a median follow-up of 9.4 months (range 2.7 to 40.1 months), 18 patients died. The 1-year local control rate was 97.4%. The 1-year progression-free survival was 50.3%. The 1-and 2-year overall survival was 72% and 53%. Approximately 85% patients experienced pain relief after SBRT. Patients who achieved complete or partial response after SBRT obtained better overall survival than those with stable disease or disease progression (1-year overall survival:83% vs. 48%,P=0.021). In the whole cohort, 6 cases developed Grade Ⅲ adverse events, 4 of which were Grade Ⅲ myelosuppression, 1 case of Grade Ⅲ neuropathy and 1 case of radiation-induced skin injury. Conclusion Preliminary study reveals that combined use of targeted therapy and SBRT is an efficacious and safe treatment of advanced mRCC.