Postoperative Stereotactic Radiosurgery for Resected Brain Metastases: A Comparison of Outcomes for Large Resection Cavities.

Abstract

Although historical trials have established the role of surgical resection followed by whole brain irradiation (WBRT), WBRT has recently been shown to cause significant neurocognitive decline. Many practitioners have employed post-operative stereotactic radiosurgery (SRS) to tumor resection cavities to increase local control without significant neurocognitive sequelae. However, there have been no significant series detailing outcomes of large brain metastases treated with resection and post-operative SRS. Here, we compare outcomes in patients with large brain metastases > 4 cm to those with smaller metastases ≤ 4 cm treated with surgical resection followed by SRS to the resection cavity. Consecutive patients with brain metastases treated at our institution with surgical resection and post-operative SRS were retrospectively reviewed. Patients were stratified into ≤ 4 cm and > 4 cm cohorts based on pre-operative maximal tumor dimension. Cumulative incidence of local failure, radiation necrosis, and death were analyzed for the two cohorts. A total of 117 consecutive cases were identified. Of these patients, 90 (77%) had pre-operative tumors were ≤ 4 cm, and 27 (23%) were > 4 cm in greatest dimension. The only significant baseline difference between the two groups was a higher proportion of patients with gross total resection of their tumors in the ≤ 4 cm compared to the > 4 cm cohort, 76% vs. 48%, (p<0.01). The 1-year rates of local failure, radiation necrosis, and overall survival for the ≤ 4 cm and > 4 cm cohorts were 12.3% and 16.0%, 26.9% and 28.4%, and 80.6% and 67.6%, respectively (all p>0.05). The rates of local failure and radiation necrosis were not statistically different on multivariable analysis based on tumor size. Brain metastases > 4 cm in largest dimension managed by resection and radiosurgery to the tumor cavity have promising local control rates without a significant increase in radiation necrosis on our retrospective review.