ORIGINAL ARTICLE Analysis of survival outcomes based on molecular subtypes in breast cancer brain metastases: A single institutional cohort Wan Jeon MD 1 | Bum‐Sup Jang MD 1 | Seung Hyuck Jeon MD 1 | Jee Hyun Kim MD, PhD 2 | Yu Jung Kim MD, PhD 2 | Se Hyun Kim MD 2 | Chae‐Yong Kim MD, PhD 3 | Jung Ho Han MD, PhD 3 | In Ah Kim MD, PhD 1,2 1 Department of Radiation Oncology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea 2 Department of Internal medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea 3 Department of Neurosurgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea Correspondence In Ah Kim, Department of Radiation Oncology, Seoul National University Bundang Hospital, Bundang‐gu, Seongnam, South Korea. Email: inah228@snu.ac.kr Funding information This work was supported by grants from the Korean Ministry of Health and Welfare (No. 0820010) and Ministry of Science and Information & Communication Technology (NRF No. 2017R1A2B4002710 & NRF No. 2017M2A2A7A01018438) to In Ah Kim. Abstract 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 dif- ferent based on the molecular subtype of the tumor, despite various local and sys- temic treatments. Appropriate and tailored treatment approaches should, therefore, be considered for the different molecular subtypes. KEYWORDS brain metastasis, breast cancer, molecular subtype 1 | INTRODUCTION Breast cancer is a known cause of brain metastases following lung cancer. 1 Approximately 15% of metastatic breast cancer patients have brain metastasis, and if an autopsy study is included, this num- ber is increased to 30%. 2,3 The current National Comprehensive Cancer Network (NCCN) treatment guidelines for brain metastasis are based on the number of metastases. Tumor removal, whole brain radiotherapy (WBRT), and stereotactic radiosurgery (SRS) are recommended in cases with 1‐3 limited metastatic lesions and WBRT or SRS is recommended for patients with more than 3 lesions. 4 However, in the current Received: 4 September 2017 | Revised: 12 November 2017 | Accepted: 16 November 2017 DOI: 10.1111/tbj.13111 Breast J. 2018;1–7. wileyonlinelibrary.com/journal/tbj © 2018 Wiley Periodicals, Inc. | 1