Breast Cancer Subtype and Distant Recurrence after Ipsilateral Breast Tumor Recurrence

There is little information about the impact of breast cancer subtype on prognosis after ipsilateral breast tumor recurrence (IBTR). One hundred eighty-five patients were classified according to breast cancer subtype, as approximated by estrogen receptor, human epidermal growth factor receptor 2 (HER2), and Ki-67, of IBTR, and we evaluated whether breast cancer subtype was associated with distant recurrence after IBTR. There was a significant difference in distant disease-free survival (DDFS) after IBTR according to breast cancer subtype defined by a cutoff of the Ki-67 index of 20 % (p = 0.0074, log-rank test). The 5-year DDFS rates for patients with luminal A, luminal B, triple-negative, and HER2 types were 86.3, 57.1, 56.6, and 65.9 %, respectively. In addition, breast cancer subtype was significantly associated with distant recurrence after IBTR on adjustment for various clinicopathologic factors (p = 0.0027, Cox proportional hazards model). Our study suggests that breast cancer subtype based on immunohistochemical staining predicts the outcomes of patients with IBTR. Further analyses are needed (UMIN-CTR number UMIN000008136).