Radiosurgery to the Postoperative Tumor Bed for Metastatic Carcinoma Versus Whole Brain Radiation After Surgery

BACKGROUND: The treatment paradigm from postoperative whole brain radiation therapy (WBRT) to post-operative stereotactic radiosurgery (SRS) to the tumor bed has shifted with little data to evaluate whether each treatment modality confers equivalent tumor control and survival outcomes. METHODS: Patients with surgical resection of single brain metastases from January 2010 to December 2014 were treated postoperatively with either WBRT or SRS. Retrospective patient data was compared for local control, distant brain recurrence, overall survival, and radiation complications. RESULTS: Forty-six received WBRT, and 37 received tumor bed SRS. Twelve of 35 (34%) SRS patients experienced local recurrence compared to 17 of 31 (55%) WBRT patients (p = 0.09). The median survival was 440 days (14.7 months) for SRS and 202 days (6.7 months) for WBRT (p = 0.062, log-rank). SRS demonstrated improved survival benefit in the first six months (p = 0.0034; Wilcoxon). Radiation-related adverse changes after SRS (22%) were not statistically different from WBRT (8.7%) (p = 0.152). Age (p = 0.08), systemic cancer status (p = 0.30), Graded Prognostic Assessment (p = 0.28), number of brain metastases at diagnosis (p = 0.65), tumor volume at diagnosis (p = 0.13), new brain lesions (p = 0.74) and neurologic versus systemic cause of death (p = 0.11) did not differ between the groups. CONCLUSIONS: Following surgical resection, tumor bed SRS can be used effectively in lieu of WBRT to treat brain metastases with comparable local control and distant control and without significantly more adverse events.