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Background: The increased incidence of brain metastasis (BM) among patients with HER2 3+ metastatic breast cancer (BC) has been documented for several years. Recently, it has been established that patients with triple negative (TN) BC also have increased incidence of BM and shorter median interval between primary diagnosis and cerebral relapse than non–triple-negative BC.

Aim: The primary objective of this study was to analyze the time to BM in patients with TN BC and HER2 3+ patients. Secondary objective was to compare the percentage of patients who underwent brain surgery accordinig to molecular marker characteristics of primary BC.

Patients and methods: A cohort of 109 BC patients with BM was identified in a 3-yr interval at the Institute for Oncology and Radiology of Serbia. All patients had histologicaly confirmed BC and CT/MRI documented BM.

Results: Median age at the time of BM was 49 (25-79). Seventeen out of 109 pts (15.5%) had incomplete molecular status of primary BC, 4 for all 3 parameters (ER,PGR, HER2) and 16 only for HER2 status. Therefore, they have been excluded from this analysis. Seventeen pts (17/92;18.4%) had TN status defined as both receptors values Quick score 0 and IHC HER2 status scored 0. Thirty one pts (31/92;33.6%) had IHC HER2 3+ BC. Median interval to BM development is presented at table 1

Conclusion: In this analysis we could not confirm that time to BM development is shorter in the patients with TN BC compared with pts with HER2 3+ BC BM. Patients with HER2 3+BC had statistically significant shorter time to BM development compared with any other BM subgroup (P=0.005). However, it seems that TN BM are more often multiple, at presentation hence only 4 pts underwent brain surgery as compared with 9 pts with HER2 3+ BCBM. That could potentially better reflect the aggressive nature of TN BM than the time to BM development.