The Impact Of Switching Systemic Treatment After Radiosurgery (Sbrt) For Oligo-Progressive, Metastatic Renal Cell Carcinoma (Mrcc).

599Background: Local therapy such as SBRT is increasingly applied to RCC metastases when progression involves a limited number of metastatic sites (oligo-progression; O-PD). We aimed to assess the clinical outcome of patients (pts) with O-PD who changed systemic treatment upon SBRT (SWITCH) compared with those who remained on same therapy after SBRT (STAY); and also with the group of pts who progressed systemically (PD-SYS) and changed systemic treatment as well. Methods: Retrospective analysis of clear-cell mRCC pts treated with SBRT to brain or spinal metastases was undertaken. Clinical outcomes and treatment duration on current therapy of pts in the SWITCH, STAY and PD-SYS groups were compared. Treatment duration was defined as the time interval between SBRT and discontinuation of current systemic therapy for STAY group and discontinuation of first subsequent therapy in the SWITCH and PD-SYS groups. Results: A total of 100 pts with mRCC who had SBRT were identified, including 44 in STAY, 23 in SWITCH a...