SURG-53. Gammatile Therapy at the Time of Resection for Brain Metastasis: A Multi-Institutional Experience

INTRODUCTION There are compelling rationales for considering brachytherapy, such as Gammatile (GT), at the time of brain metastasis (BM) resection, including superior radiation dosimetry, timely radiation delivery, and minimizing the burden of repeated hospital visits. While such practice is documented in recurrent BM, there is limited information on its use for newly diagnosed BM (nBM). Here, we report the outcome of 36 nBM patients who underwent resection/GT implant. METHODS Clinical information was collected for consecutive n BM patients treated at the University of Minnesota, Westchester Medical Center, and Brown University. Actuarial local control and overall survival (mOS) were calculated from the time of GT implant. RESULTS The cohort comprised 17 men and 19 women (mean age: 61.9 ± 8.66 years). The histology included: 19 lung, 8 melanoma, 5 breast, 3 gastrointestinal, and 1 valvular cancer. The mean diameter of the resected BM was 3.28 ± 1.35 cm. Gross total resection was achieved in all but one subject. The number of GT used ranged 4-12 (median of 6). The average Karnofsky Performance Score (KPS) before resection/GT implant was 81 ± 11.1; There were no peri-operative complications, with the average hospital stay of 2.2 ± 1.6 days. There were eight 30-day readmissions (22%). KPS improved/remained stable for 29 patients and worsened in 7. With the median follow-up of 328 days, the actuarial local control at one year was 91.7%. The median overall survival (OS) of the cohort was 182 days. Pre-operative KPS did not associate with OS (77 vs. 199 days, p=0.232). However, patients whose KPS declined after the resection showed shorter OS (65 vs. 211 days, p=0.02). CONCLUSION This series is the largest to date documenting GT for newly diagnosed BM, with a highly favorable safety and efficacy. KPS decline post-resection is associated with poor survival, emphasizing the importance of a “safe” resection.