Effect of molecular subtypes on radiotherapy response in patients with breast cancer brain metastasis

Abstract

Objective: This study aimed to investigate survival and the response to radiotherapy (RT) among patients with molecular subtypes of breast cancer brain metastases. Patients and Methods: We retrospectively analyzed the data of 139 breast cancer patients with brain metastases treated with wholebrain radiotherapy (WBRT) or focal brain treatment (FBT) between 2006 and 2019. Overall survival (OS) and brain metastasis progression-free survival (BMPFS) were calculated from the first RT until death or the last follow-up. Survival analyses were performed using the Kaplan–Meier method. Prognostic factors were evaluated using the Cox proportional hazard model. Results: Twenty three (16.5%), 77 (55.4%), 14 (10.1%), and 25 (18%) patients were diagnosed with triple-negative, HER-2 (+), luminal-like A, and luminal-like B breast cancer, respectively. Of 139 patients, 66 (47.8%) underwent FBT, and 73 (52.5%) underwent WBRT. While the most preferred fraction was 10*300 Gy in WBRT, doses of 15-25 Gy in 1-5 fractions were preferred in local RT. We observed that age, Karnofsky performance scale (KPS) score, initial RT technique, extracranial disease, number of brain metastases impacted OS and BMPFS. Conclusion: Breast cancer brain metastasis is a different, complex, and challenging disease based on the molecular subtype of the tumor, despite various local treatments. Therefore, appropriate and tailored treatment approaches should be considered for the different molecular subtypes.