Objective: Stereotactic radiosurgery (SRS) is an effective treatment for intracranial metastatic disease, but its role in triple-negative breast cancer requires further study. Herein, the authors report overall survival (OS) and local tumor control in a multiinstitutional cohort with triple-negative breast cancer metastases treated with SRS.
Methods: Patients treated from 2010 to 2019 at 9 institutions were included in this retrospective study if they had biopsy-proven triple-negative breast cancer with intracranial metastatic lesions treated with SRS. Patients were excluded if they had undergone prior SRS, whole-brain radiation therapy, or resection of the metastatic lesions. A retrospective chart review was conducted to determine OS, local control, and treatment efficacy.
Results: Sixty-eight patients with 315 treated lesions were assessed. Patients had a median Karnofsky Performance Status of 80 (IQR 70-90) and age of 57 years (IQR 48-67 years). Most treated patients had 5 or fewer intracranial lesions, with 34% of patients having a single lesion. Treated lesions were small, having a median volume owf 0.11 cm3 (IQR 0.03-0.60 cm3). Patients were treated with a median margin dose of 18 Gy (IQR 18-20 Gy) to the median 71% isodose line (IQR 50%-84%). Overall, patients had a 1-year OS of 43% and 2-year OS of 20%. Most patients (88%) were followed until death, by which time local tumor progression had occurred in only 7% of cases. Furthermore, 76% of the lesions demonstrated regression. Tumor volume was correlated with local tumor progression (p = 0.012). SRS was very well tolerated, and only 3 patients (5%) developed symptomatic radiation necrosis.
Conclusions: SRS is a safe and efficacious treatment for well-selected patients with triple-negative breast cancer, especially for those with a favorable performance status and small- to moderate-volume metastatic lesions.
Keywords: Gamma Knife; SRS; brain metastases; breast cancer; oncology; stereotactic radiosurgery; triple negative.