Locoregional Recurrence by Tumor Biology in Breast Cancer Patients after Preoperative Chemotherapy and Breast Conservation Treatment

PURPOSE The purpose of this study is to determine whether breast cancer subtype can affect locoregional recurrence (LRR) and ipsilateral breast tumor recurrence (IBTR) after neoadjuvant chemotherapy (NAC) and breast-conserving therapy (BCT). MATERIALS AND METHODS We evaluated 335 consecutive patients with clinical stage II-III breast cancer who received NAC plus BCT from 2002 to 2009. Patients were classified according to six molecular subtypes: luminal A (hormone receptor [HR]+/HER2-/Ki-67 < 15%, n=113), luminal B1 (HR+/HER2-/Ki-67 ≥ 15%, n=33), luminal B2 (HR+/HER2+, n=83), HER2 with trastuzumab (HER2[T+]) (HR-/HER2+/use of trastuzumab, n=14), HER2 without trastuzumab (HER2[T-]) (HR-/HER2+, n=31), and triple negative (TN) (HR-/HER2-, n=61). RESULTS After a median follow-up period of 7.2 years, 26 IBTRs and 37 LRRs occurred. The 5-year LRR-free survival rates were luminal A, 96.4%; B1, 93.9%; B2, 90.3%; HER2(T+), 92.9%; HER2(T-), 78.3%; and TN, 79.6%. The 5-year IBTR-free survival rates were luminal A, 97.2%; B1, 93.9%; B2, 92.8%; HER2(T+), 92.9%; HER2(T-), 89.1%; and TN, 84.6%. In multivariate analysis, HER2(T-) (IBTR: hazard ratio, 4.2; p=0.04 and LRR: hazard ratio, 7.6; p < 0.01) and TN subtypes (IBTR: hazard ratio, 6.9; p=0.01 and LRR: hazard ratio, 8.1; p < 0.01) were associated with higher IBTR and LRR rates. A pathologic complete response (pCR) was found to show correlation with better LRR and a tendency toward improved IBTR controls in TN patients (IBTR, p=0.07; LRR, p=0.03). CONCLUSION The TN and HER2(T-) subtypes predict higher rates of IBTR and LRR after NAC and BCT. A pCR is predictive of improved IBTR or LRR in TN subtype.