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.
Keywords: Breast neoplasms; Ipsilateral breast tumor recurrence; Local neoplasm recurrence; Molecular subtype; Neoadjuvant chemotherapy.