Characterization of Treatments and Disease Course for Women with Breast Cancer Brain Metastases: 5-Year Retrospective Single Institution Experience

Sonya Chew,1 Hailey Kathryn Carroll,1 Waseem Darwish,1 Oleksandr Boychak,2 Michaela Higgins,1 John McCaffrey,1 Catherine Margaret Kelly1 1Department of Medical Oncology, Mater Misericordiae University Hospital, Dublin, Ireland; 2Department of Radiation Oncology, St Luke’s Radiation Oncology Network, Beaumont Hospital, Dublin, IrelandCorrespondence: Sonya ChewMater Misericordiae University Hospital, Eccles Street, Dublin 7, Dublin, D07R2WY, IrelandTel +35318032000Fax +35318032113Email sonya_chew@yahoo.comPurpose: Around 30% of patients with breast cancer will develop brain metastases (BM). We sought to characterize the disease course, treatments and outcome for our patient cohort.Materials and Methods: We extracted clinicopathological data from electronic records from January 2015 to December 2020. Results were generated using SPSS statistics v27.Results: We identified 98 patients. Median overall survival (OS) from BM diagnosis was 3 months [hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)–], 8 months [HR+/HER2+], 7 months [HR–/HER2+] and 2 months [triple negative breast cancer (TNBC)]. Whole brain radiotherapy (WBRT) (n=48, 70%) was most frequently used followed by surgery (n=15, 22%) and stereotactic radiosurgery (n=6, 8%). In patients who received WBRT alone (n=40) the median OS post WBRT was 2.6 months.Conclusion: After BM development, half of the patients had systemic therapy and 70% had local therapy, but only the HER2 subgroup had a prolonged OS likely reflecting central nervous system (CNS) activity of anti-HER2 drugs. TNBC patients had the worst prognosis. Although our cohort is small, OS was > 1 year for 60% of HER2+ patients who received trastuzumab emtansine after BM development, which is encouraging for antibody drug conjugates and CNS activity. Patients who received WBRT had a higher burden of CNS disease and had an OS of less than 3 months.Keywords: metastatic, breast cancer, brain metastases, treatment, triple negative