A boost in addition to whole-brain radiotherapy improves patient outcome after resection of 1 or 2 brain metastases in recursive partitioning analysis class 1 and 2 patients

BACKGROUND: The current study was conducted to compare 2 treatment regimens including surgical resection and whole-brain radiotherapy (WBRT) for patients with 1 to 2 brain metastases. METHODS: A total of 201 patients with recursive partitioning analysis (RPA) class 1 to 2 disease with 1 to 2 resectable brain metastases were analyzed retrospectively. Patients underwent either resection of the metastases plus WBRT with 10 fractions of 3 grays (Gy) each or 20 fractions of 2 Gy each (99 patients; Group A) or the same treatment plus a WBRT boost to the metastatic site (10 fractions of 3 Gy each plus 5 fractions of 3 Gy each or 20 fractions of 2 Gy each plus 5 fractions of 2 Gy each) (102 patients; Group B). Eight other potential prognostic factors were evaluated with regard to overall survival (OS), brain control (BC), and local control of resected metastases (LC): age, gender, Karnofsky performance status, extent of surgical resection, tumor type, extracranial metastases, RPA class, and interval from tumor diagnosis to WBRT. RESULTS: Group B patients had better 1-year OS (66% vs 41%; P < .001). On multivariate analysis of OS, treatment regimen (relative risk RR] of 1.94; P < .001), extent of surgical resection (RR of 1.80; P = .001), and interval from tumor diagnosis to WBRT (RR of 1.62; P = .010) were found to be statistically significant. On multivariate analysis of BC, treatment regimen (RR of 2.15; P = .002), extent of surgical resection (RR of 2.78; P < .001), and interval from tumor diagnosis to WBRT (RR of 1.52; P = .034) were found to be statistically significant. On multivariate analysis of LC, treatment regimen (RR of 2.31; P = .002) and extent of surgical resection (RR of 3.79; P < .001) were found to be statistically significant. On RPA class subgroup analyses, outcome was found to be significantly better with a WBRT boost in both RPA class 1 and class 2 patients. A WBRT boost resulted in better outcome after both complete and incomplete surgical resection. However, the results concerning BC and LC were not found to be statistically significant if surgical resection was incomplete. CONCLUSIONS: After surgical resection of 1 to 2 brain metastases, a boost of 10 to 15 Gy in addition to WBRT was found to improve outcome. After incomplete surgical resection, further dose escalation to the metastatic site may be considered.