Clinical features and course of brain metastases in triple-negative breast cancer: comparison with human epidermal growth factor receptor 2-positive and other type at single institution in Korea

The incidences and clinical aggressiveness of intracranial metastases have not been as well characterized in patients with triple-negative (TN) breast cancer as in patients with human epidermal growth factor 2-positive (HER2+) breast cancer. Patients diagnosed with brain metastases from primary breast cancer, as determined by computed tomography and/or magnetic resonance imaging, at Asan Medical Center from January 1990 to July 2006 were identified and classified into three subtypes: TN, HER2+, and other. The clinical features and outcomes of these three groups were compared. Of the 7,872 patients diagnosed with primary breast cancer, 198 developed brain metastases; of these, 61 patients with unknown estrogen receptor, progesterone receptor, and HER2 status were excluded. Of the remaining 137 patients, 44 (32%) were classified as TN, 69 (50%) as HER2+, and 24 (18%) as other. Clinical parameters, including performance status and previous adjuvant chemotherapy and/or radiotherapy, were well balanced among groups, except that earlier staged tumors (I and II) were more prevalent in the TN than in the HER2+ and other (59 vs. 36 vs. 38%, P = 0.01). At a median follow-up of 99 months, the median times from initial diagnosis to brain metastasis (20 vs. 32 vs. 45 months, P = 0.01) and to first distant metastasis at any site (16 vs. 23 vs. 23 months, P = 0.005) were significantly shorter in TN than in the HER2+ and other. Median overall survival (OS) from primary cancer diagnosis was significantly shorter in the TN than in the HER2+ and other (31 vs. 39 vs. 57 months, P = 0.02), but survival after brain metastasis was similar (5.9 vs. 5.2 vs. 8.8 months, P = 0.31). Compared with other breast cancer phenotypes, TN breast cancer was characterized by earlier brain and other distant metastases and shorter OS, despite a higher proportion of tumors diagnosed at early stages.