SAbR For Oligometastatic Renal Cell Carcinoma

Hypothesis: Stereotactic ablative body radiation (SAbR) prolongs progression-free survival for patients with oligometastatic kidney cancer (RCC) and delays the initiation of systemic therapy. Primary Objectives: • To evaluate the delay in time to start of systemic therapy (TTST) as a surrogate of progression free survival (PFS), defined as the time from the first day of SAbR to start of systemic therapy. Secondary Objective: * To evaluate the modified progression-free survival (mPFS) for patients with oligometastatic renal cell carcinoma who are treated with SAbR. * To evaluate the overall survival (OS) * To evaluate the cancer specific survival (CSS) * To evaluate the local control rate of irradiated lesions. * To measure the health-related quality of life (HRQOL).