Thoracic Radiotherapy for Renal Cell Carcinoma Metastases: Local Control for the Management of Lung and Mediastinal Disease in the Modern Era

Introduction/Background: Radiotherapy (RT) is an alternative local therapy to metastasectomy in the treatment of thoracic metastases from renal cell carcinoma (RCC), including the management of life-threatening disease. Patients and Methods: We reviewed patients with lung and mediastinal RCC metastases treated with RT at our institution. Overall survival (OS) and metastasis control (MC) was measured from the start of RT using the Kaplan-Meier (KM) method. Results: Seventy-one patients were treated with RT for 89 lung (n = 58) or mediastinal (n = 31) metastases. Of 89 treated lesions, 11 (12%) had local tumor recurrence, at a median of 1.6 years (range 0.4-2.9). MC at 1, 3, and 5-years was 96.6%, 83.5%, and 67.9%, respectively. For the 58-lung metastasis-directed RT courses, MC rates at 1, 3, and 5-years were 95.0%, 84.5%, and 84.5%, respectively (median MC not reached). For the 31-mediastinum metastasis-directed RT courses, MC rates at 1, 3, and 5-years were 100%, 43.4%, and 43.4%, respectively (median MC 2.9 years). MC was significantly improved for lung lesions compared to mediastinal lesions (P = .046). OS for the entire cohort at 1, 3, and 5 years was 65.2%, 48.5%, and 38.0%. There was no difference in OS based on metastatic sites in the 71 patients. Nineteen patients received RT to 19 lesions with the intention of preventing an event such as airway compromise or vascular invasion. One and two-year MC for these 19 lesions were 88.9% and 71.1%, respectively (median local control 2.4 years). OS in these 19 patients at 1, 2, and 5 years were 62.1%, 48.3%, and 32.2% respectively, with median survival 1.2 years. No patients developed grade 4 or 5 acute or late toxicities. Conclusion: Radiation therapy can safely achieve high metastasis control rates for lung and mediastinal metastases from RCC, including lesions at high risk for causing a life-threatening event.