Prospective Randomized Trial of Post-operative Stereotactic Radiosurgery versus Observation for Completely Resected Brain Metastases

BACKGROUND: After brain metastasis resection, whole-brain radiation therapy (WBRT) decreases local recurrence but may cause cognitive decline. We performed this study to determine if stereotactic radiosurgery (SRS) to the surgical cavity improved local tumor tumor-free recurrence rates compared to surgical resection alone as an alternative to the need for immediate WBRT. METHODS: The main entry criteria for the study included patients >3 years of age, with a Karnofsky Performance Score ≥ 70, who were able to undergo an MRI scan and who had a complete resection of 1–3 brain metastases (the maximum diameter of the resection cavity had to be ≤4cm). Patients were assigned randomly to either SRS treatment of the resection cavity (within 30 days of surgery) or observation (OBS). Patients were stratified by histology, tumor size, and number of metastases. Patients were recruited at a single tertiary cancer center. The primary endpoint was time to local recurrence in the resection cavity assessed by blinded central review of brain MRI scans in the intention-to-treat population. The trial was registered at clinicaltrials.gov (Trial NCT00950001, status: closed to new participants). FINDINGS: Between 8/13/2009 and 2/16/2016, 132 patients were randomized to OBS (N=68) or SRS (N=64), with 128 patients available for analysis. We stratified by metastasis size (maximum diameter of ≥3 cm vs. <3 cm), histology (melanoma vs. other), and number of metastases (one vs. two or three). The 12-month local tumor recurrence-free rate was 43% (OBS) (95% CI 31%–59%) and 72% (SRS) (95% CI 60%–87%) (hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.24–0.88, p=0.015). INTERPRETATION: This prospective randomized trial of patients undergoing surgical resection for 1–3 brain metastases indicates that SRS administered to the resection cavity significantly lowers local recurrence compared to observation alone. Thus, the use of SRS after brain metastasis resection is an alternative to WBRT.