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.