Analysis of survival outcomes based on molecular subtypes in breast cancer brain metastases: A single institutional cohort

Purpose To evaluate the survival outcomes based on molecular subtypes of breast cancer in patients with brain metastasis. Materials and methods We retrospectively reviewed 106 breast cancer patients treated for brain metastases, from January 2005 to May 2016. Patients were divided into four groups based on the tumor molecular subtype: luminal A (Estrogen Receptor [ER]/Progesterone Receptor [PR] positive, human epithelial growth factor receptor-2 [HER2] negative), luminal B (ER/PR positive, HER2 Positive), HER2 (HER2 positive and ER/PR negative), and Triple negative (TNBC). Results The median follow-up time for surviving patients was 22 months (range: 11.2-51.1 months). The median survival of all patients was 14 months, with a 1-year overall survival (OS) rate of 57.5% and a 2-year OS rate of 32.1%. Thirty patients (28.3%) had a solitary brain metastasis while 62 (58.5%) patients had multiple metastases. A significant difference was observed in the survival rates of the two groups. Based on the Karnofsky performance score, the performance status of the patients at the time of brain metastasis was also found to affect survival. Patients with different molecular subtypes had different survival rates; the luminal A group showed the highest median survival (luminal A: 23.1, luminal B: 15.0, HER2: 12.5 and TNBC: 6.4 months, respectively), which was statistically significant. Conclusion In breast cancer patients with brain metastasis, survival rates were different based on the molecular subtype of the tumor, despite various local and systemic treatments. Appropriate and tailored treatment approaches should, therefore, be considered for the different molecular subtypes.