BMET-32OUTCOMES OF GAMMA KNIFE RADIOSURGERY IN BRAIN METASTASES FROM NEUROENDOCRINE TUMORS

Abstract

BACKGROUND: Neuroendocrine tumors (NETs) can originate in any organ but most commonly arise from the lungs. Despite cranial irradiation, small cell lung cancer (SCLC) often metastasizes to the brain. Stereotactic radiosurgery (SRS) is an established treatment for brain metastases yet little is known about the utility of SRS in the treatment of NETs especially noting their unique natural history. METHODS: Thirty-three patients with brain metastases from NETs who underwent Gamma Knife radiosurgery (GKRS) were retrospectively reviewed. Median age and Karnofsky performance status were 61 years (range, 30-76 years) and 80 (range, 60-90), respectively. Primary site was lung (87.9%), cervix (6.1%), esophagus (3%) and prostate (3%). Ten patients (30.3%) received upfront GKRS, 7 of whom had NETs other than SCLC. Kaplan-Meier survival and Cox regression analyses were performed to determine prognostic factors for survival. RESULTS: Of 130 evaluable lesions, 116 (89.2%) showed complete or partial response 4 to 6 weeks after GKRS. With median follow-up of 5.3 months, local and distant brain recurrence occurred in 1 patient (3.3%) and 20 patients (66.7%), respectively. The 6 and 12-month local (LRFS) and distant brain recurrence-free survival (DBRFS) were 100%/84% and 40.1%/29.3%, respectively. Median overall survival (OS) after GKRS was 6.9 months. Upfront GKRS and more than 1 GKRS course were prognostic for better OS and the number of brain metastases was prognostic for DBRFS on multivariate analyses. Toxicity developed in 13 lesions (10%) in 9 patients; hemorrhage (n = 2 lesions), necrosis (n = 8 lesions) and edema requiring steroids (n = 10 lesions). No cases of grade 3 or higher necrosis occurred. Patients treated with whole brain radiation prior to GKRS did not have higher toxicity rates than patients treated with upfront GKRS. CONCLUSIONS: GKRS is an effective treatment option for patients with brain metastases from NETs with excellent local control despite slightly higher toxicity rates than expected.