Local control of brain metastases after stereotactic radiosurgery: the impact of whole brain radiotherapy and treatment paradigm.

Purpose: We investigate clinical, pathologic, and treatment paradigm-related factors affecting local control of brain metastases after stereotactic radiosurgery (SRS) with or without whole brain radiotherapy (WBRT). Methods and materials: Patients with brain metastases treated with SRS alone, before or after WBRT were considered to determine predictors of local failure (LF), time to failure and survival. Results: Among 137 patients, 411 brain metastases were analyzed. 23% of patients received SRS alone, 51% received WBRT prior to SRS, and 26% received SRS followed by WBRT. LF occurred in 125 metastases: 63% after SRS alone, 20% after WBRT then SRS, and 22% after SRS then WBRT. Median time to local failure was significantly less after SRS alone compared to WBRT then SRS (12.1 v. 22.7 months, p=0.003). Tumor volume was significantly associated with LF (HR:5.2, p<0.001, 95% CI:3.4-7.8). Conclusions: WBRT+SRS results in reduced LF. Local control was not significantly different after SRS as salvage therapy versus upfront SRS.