Postoperative stereotactic radiosurgery to the resection cavity for large brain metastases: clinical outcomes, predictors of intracranial failure, and implications for optimal patient selection.

BACKGROUND: Postoperative stereotactic radiosurgery for brain metastases potentially offers similar local control rates and fewer long-term neurocognitive sequelae compared to whole brain radiation therapy, although patients remain at risk for distant brain failure (DBF).
OBJECTIVE: To describe clinical outcomes of adjuvant stereotactic radiosurgery for large brain metastases and identify predictors of intracranial failure and their implications on optimal patient selection criteria.
METHODS: We performed a retrospective review on 100 large (>3 cm) brain metastases in 99 patients managed by resection followed by postoperative stereotactic radiosurgery to a median dose of 22 Gy (range, 10-28) in 1 to 5 fractions (median, 3). Primary histology was nonsmall cell lung in 40%, breast cancer in 18%, and melanoma in 17%. Forty (40%) patients had uncontrolled systemic disease.
RESULTS: With a median follow-up of 12.2 months (range, 0.6-87.4), the 1-year Kaplan-Meier local control was 72%, DBF 64%, and overall survival 55%. Nine patients (9%) developed evidence of radiation injury, and 6 (6%) developed leptomeningeal disease. Uncontrolled systemic disease (P=.03), melanoma histology (P=.04), and increasing number of brain metastases (P<.001) were significant predictors of DBF on Cox multivariate analysis. Patients with <4 metastases, controlled systemic disease, and nonmelanoma primary (n=47) had a 1-year DBF of 48.6% vs 80.1% for all others (P=.01).
CONCLUSION: Postoperative stereotactic radiosurgery to the resection cavity safely and effectively augments local control of large brain metastases. Patients with <4 metastases and controlled systemic disease have significantly lower rates of DBF and are ideal treatment candidates.