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Clinical outcomes in patients with brain metastases from breast cancer treated with single-session radiosurgery or whole brain radiotherapy.

OBJECTIVE Gamma Knife radiosurgery (GKRS) is used to treat brain metastases from breast cancer (BMB) as the sole treatment or in conjunction with tumor resection and/or whole brain radiotherapy (WBRT). This study evaluates outcomes in BMB based on treatment techniques and tumor biological features. METHODS The authors reviewed all patients treated with BMB between 2004 and 2014. Patients were identified from a prospectively collected radiosurgery database and institutional tumor registry; 214 patients were identified. Data were collected from aforementioned sources and supplemented with chart review where needed. Independent radiological review was performed for all available brain imaging in those treated with GKRS. Survival analyses are reported using Kaplan-Meier estimates. RESULTS During the 10-year study period, 214 patients with BMB were treated; 23% underwent GKRS alone, 46% underwent a combination of GKRS and WBRT, and 31% underwent WBRT alone. Median survival after diagnosis of BMB in those treated with GKRS alone was 21 months, and in those who received WBRT alone it was 3 months. In those treated with GKRS plus WBRT, no significant difference in median survival was observed between those receiving WBRT upfront or in a salvage setting following GKRS (19 months vs 14 months, p = 0.63). The median survival of patients with total metastatic tumor volume of ≤ 7 cm3 versus > 7 cm3 was 20 months vs 7 months (p < 0.001). Human epidermal growth factor receptor-2 (Her-2) positively impacted survival after diagnosis of BMB (19 months vs 12 months, p = 0.03). Estrogen receptor status did not influence survival after diagnosis of BMB. No difference was observed in survival after diagnosis of BMB based on receptor status in those who received WBRT alone. CONCLUSIONS In this single-institution series of BMB, the addition of WBRT to GKRS did not significantly influence survival, nor did the number of lesions treated with GKRS. Survival after the diagnosis of BMB was most strongly affected by Her-2 positivity and total metastatic tumor volume.