BACKGROUNDThe incidence of brain metastases in patients with breast cancer is approximately 10% - 16%, and survival after diagnosis of brain metastases is usually short. This study was designed to evaluate the risk factors associated with brain metastases in advanced breast cancer patients, with a view to help predict patient groups with high risk of brain metastases.

METHODSIn total, 295 patients with advanced breast cancer were evaluated. All patients were pathologically confirmed and metastatic lesions were confirmed pathologically or by imaging. All patients were examined at least once every 6 months with head CT or MRI. Patients showing symptoms underwent immediate inspection, and brain metastatic lesions were confirmed by head CT and/or MRI.

RESULTSAt a median follow-up of 12 months from the occurrence of metastases, brain metastases had occurred in 49 patients (16.6%). In our univariate analysis, variables significantly related to increased risk of brain metastases were hormone receptor-negative tumors, epidermal growth factor receptor 2 (HER2)-positive tumors, and multiple distant metastases. Patients with dominant tumor sites in soft tissue, or defined as Luminal A subtype, tended to have a lower risk of brain metastases than patients with visceral metastases, Luminal B subtype, triple-negative subtype or HER2-enriched subtype tumors.

CONCLUSIONSOur results strongly suggest that factors such as Luminal B, triple-negative, and HER2-enriched subtypes are high risk factors for brain metastases. These data, therefore, provide pivotal clinical evidence towards a comprehensive understanding of the risk factors of brain metastases in advanced breast cancer patients.