Purpose As survival of patients with central nervous system (CNS) metastases from breast cancer is poor and incidence rates are increasing, there is a growing need for better treatment strategies. In the current study, the e cacy of local and systemic therapies was analyzed in breast cancer patients with CNS metastases.Methods Medical records from patients with breast cancer and brain and/or leptomeningeal metastases treated at a tertiary referral center and a teaching hospital between 2010 and 2020 were retrospectively studied. Main outcomes of interest were overall survival and CNS progression free survival. Analyses were performed for the different systemic and local therapies for CNS metastases, and subgroups based on breast cancer subtypes and brain metastases vs leptomeningeal metastases were tested. ResultsWe identi ed 155 patients, 44 HER2-positive, 68 hormone receptor positive/HER2-negative and 43 triple negative. Median overall survival was 5.9 months for all 155 analyzed patients. Survival differed signi cantly between breast cancer subtypes (HER2positive 22.8 months, hormone receptor positive/HER2-negative 2.4 months, triple negative 4.2 months, P<0.001). Patients receiving a combination of local and systemic therapy demonstrated prolonged median overall survival (18.5 months) as compared to local therapy only (5.7 months) or systemic therapy only (4.3 months, P<0.001). No signi cant difference in overall survival was observed between different systemic treatment regimens.Conclusion Breast cancer patients with CNS metastases show longest median overall survival when the subtype is HER2-positive and when they are treated with both local and systemic therapy.

Purpose As survival of patients with central nervous system (CNS) metastases from breast cancer is poor and incidence rates are increasing, there is a growing need for better treatment strategies. In the current study, the efficacy of local and systemic therapies was analyzed in breast cancer patients with CNS metastases.Methods Medical records from patients with breast cancer and brain and/or leptomeningeal metastases treated at a tertiary referral center and a teaching hospital between 2010 and 2020 were retrospectively studied. Main outcomes of interest were overall survival and CNS progression free survival. Analyses were performed for the different systemic and local therapies for CNS metastases, and subgroups based on breast cancer subtypes and brain metastases vs leptomeningeal metastases were tested.Results We identified 155 patients, 44 HER2-positive, 68 hormone receptor positive/HER2-negative and 43 triple negative. Median overall survival was 5.9 months for all 155 analyzed patients. Survival differed significantly between breast cancer subtypes (HER2-positive 22.8 months, hormone receptor positive/HER2-negative 2.4 months, triple negative 4.2 months, P<0.001). Patients receiving a combination of local and systemic therapy demonstrated prolonged median overall survival (18.5 months) as compared to local therapy only (5.7 months) or systemic therapy only (4.3 months, P<0.001). No significant difference in overall survival was observed between different systemic treatment regimens.Conclusion Breast cancer patients with CNS metastases show longest median overall survival when the subtype is HER2-positive and when they are treated with both local and systemic therapy.