Outcomes and recurrence patterns according to breast cancer subtypes in Korean women.

The aim of this study was to evaluate the outcomes and patterns of recurrence in the different subtypes of breast cancer. We analyzed 1432 stage I-III breast cancer patients who had undergone surgery at Seoul National University Bundang Hospital between June 2003 and August 2011. Five subtypes were defined according to estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 (HER2), and Ki-67. Overall survival (OS) and breast cancer-free interval (BCFI) rates were estimated using the Kaplan-Meier method. Site-specific recurrence was estimated using Gray's test. The median follow-up period was 53 months. There were 22 local recurrences, 18 cases of contralateral breast cancer, 19 regional nodal recurrences, and 70 distant metastases. The 5-year BCFIs by subtype were luminal B-HER2 (+), 94.2 %; luminal A, 93.9 %; luminal B-HER2 (-), 91.4 %; HER2, 83.1 %; and triple-negative, 81.9 % (p < 0.001). Cases with the luminal A had a 5-year OS rate of 98.3 % that was the longest compared to those of cases with luminal B-HER2 (-), 95.8 %; luminal B-HER2 (+), 98.0 %; HER2, 90.8 %; and triple-negative, 89.9 % (p < 0.001). The triple-negative had a higher rate of local recurrence at the first site than others (p = 0.013). HER2 and triple-negative had higher rates of nodal recurrence at the first site than others (p < 0.001). The outcomes and patterns of site-specific recurrence in Korean breast cancer patients were different for each subtype. Defining recurrence patterns by breast cancer subtypes can help determine the appropriate method of surveillance and treatment.