Stereotactic Body Radiotherapy for the Treatment of Oligometastatic Renal Cell Carcinoma

Abstract

Renal cell carcinoma (RCC) is considered radioresistant, but stereotactic radiosurgery can control intracranial metastases. Advances in radiotherapy, such as stereotactic body radiotherapy (SBRT), allow high-dose radiation delivery to extracranial sites. Herein, we report our experience treating oligometastatic RCC with SBRT. Patients with RCC and limited metastases were treated on a 3-fraction dose-escalation protocol (8 to 14 Gy/fraction) or off protocol with 10 fractions (4 to 5 Gy/fraction). Disease control was evaluated with serial imaging, and the Kaplan-Meier method was used to estimate lesion control (LeC), distant control, and survival. Eighteen consecutively treated patients with 39 metastases were treated using SBRT; 12 underwent treatment for all metastatic sites. Median follow-up was 16.2 months. Treatment was well tolerated; the most common acute toxicity was fatigue (61.1%) and late toxicity was limited. At 2 years, LeC was 91.4% and overall survival was 85%. Those who underwent treatment for all metastatic sites had a 2-year LeC of 100% and distant control of 35.7%. A shorter interval from diagnosis to SBRT predicted for distant progression. Freedom from any post-SBRT therapy was 64.2% at 1 year. In metastatic RCC, SBRT produces promising LeC with minimal toxicity. Further study should be expanded beyond that of managing intracranial disease. Its selected use may delay the requirement for systemic therapies.