Factors affecting locoregional recurrence in breast cancer patients undergoing surgery following neoadjuvant treatment

BACKGROUND: Neoadjuvant chemotherapy (NAC) has been the standard treatment for locally advanced breast cancer for the purpose of downstaging or for conversion from mastectomy to breast conservation surgery (BCS). Locoregional recurrence (LRR) rate is still high after NAC. The aim of this study was to determine predictive factors for LRR in breast cancer patients in association with the operation types after NAC. METHODS: Between 2005 and 2017, 1047 breast cancer patients underwent BCS or mastectomy after NAC in Chang Gung Memorial Hospital, Linkou. We obtained data regarding patient and tumor characteristics, chemotherapy regimens, clinical tumor response, tumor subtypes and pathological complete response (pCR), type of surgery, and recurrence. RESULTS: The median follow-up time was 59.2 months (range 3.13–186.75 months). The mean initial tumor size was 4.89 cm (SD ± 2.95 cm). Of the 1047 NAC patients, 232 (22.2%) achieved pCR. The BCS and mastectomy rates were 41.3% and 58.7%, respectively. One hundred four patients developed LRR (9.9%). Comparing between patients who underwent BCS and those who underwent mastectomy revealed no significant difference in the overall LRR rate of the two groups, 8.8% in BCS group vs 10.7% in mastectomy group (p = 0.303). Multivariate analysis indicated that independent factors for the prediction of LRR included clinical N2 status, negative estrogen receptor (ER), and failure to achieve pCR. In subgroups of multivariate analysis, only negative ER was the independent factor to predict LRR in mastectomy group (p = 0.025) and hormone receptor negative/human epidermal growth factor receptor 2 positive (HR−/HER2 +) subtype (p = 0.006) was an independent factor to predict LRR in BCS patients. Further investigation according to the molecular subtype showed that following BCS, non-pCR group had significantly increased LRR compared with the pCR group, in HR−/HER2 + subtype (25.0% vs 8.3%, p = 0.037), and HR−/HER2− subtype (20.4% vs 0%, p = 0.002). CONCLUSION: Clinical N2 status, negative ER, and failure to achieve pCR after NAC were independently related to the risk of developing LRR. Operation type did not impact on the LRR. In addition, the LRR rate was higher in non-pCR hormone receptor-negative patients undergoing BCS comparing with pCR patients.