Resection Cavity Dynamics Following Implantation of Cesium-131 (Cs-131) Brachytherapy for Resection Brain Metastases Based on CT-Planning

months). When analyzing the time to recurrence in 2 month intervals, the highest rates of local brain failure occurred between 6-12 months after SRS. The highest rates of distant brain failure occurred between 4-12 months after SRS. Salvage options include SRS and WBRT; 12 patients (16%) were eventually salvaged by WBRT. Median overall survival was 18 months. Conclusions: For patients with a resected single brain metastasis treated with post-op SRS, local and distant brain failures were highest 4-12 months after radiosurgery. Therefore, surveillance imaging should be most frequent, possibly every 2 months, during the first year post-treatment and the frequency could be decreased thereafter. Author Disclosure: K. Kalakota: None. S.S. Rakhra: None. O. Hideki: None. I. Helenowski: None. M.H. Marymont: None. J.A. Kalapurakal: None. J.P. Chandler: None. M.P. Mehta: G. Consultant; Abbott, BristolMeyers-Squibb, Elekta, Genentech, Merck, Novartis, Novocure, Viewray. L. Stock Options; Accuray, Pharmacyclics. Q. Leadership; Pharmacyclics.