Actual Conversion Rate from Total Mastectomy to Breast Conservation after Neoadjuvant Chemotherapy for Stages II–III Breast Cancer Patients

ABSTRACT

PURPOSE: Neoadjuvant chemotherapy (NCT) is a treatment modality that increases the breast-conserving rate in breast cancer. This prospective study was performed to evaluate the actual breast-conserving rate using NCT in a clinical setting in a single institution. METHODS: Between 2014 and 2015, 265 patients who were scheduled to receive NCT and surgery were enrolled in this study. Patients were classified into three groups based on the immunohistochemical results of estrogen receptor (ER)/progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) ER or PR positive (luminal), ER/PR negative and HER2 positive (HER2+), and triple-negative breast cancer (TNBC). Before starting and immediately after completing NCT, a surgeon decided if breast-conserving surgery (BCS) or total mastectomy (TM) should be performed. We analyzed the rate of type of surgery performed. RESULTS: Before administering NCT, 107 patients (40.4%) and 158 patients (59.6%) were candidates for BCS and TM, respectively. Of the 158 patients, 61 were eligible for BCS after chemotherapy, with a conversion rate of 38.6%. NCT increased the BCS eligible rate from 40.4% to 62.6%. Of the 61 patients, 53 chose to undergo BCS, and BCS was successful in 46 (86.8%). Of the 107 BCS candidates at baseline, 100 patents finally underwent BCS (93.5%). According to the subtype, the conversion rates were 35.4%, 50.0%, and 40.5% for luminal, HER2+, and TNBC groups, respectively. CONCLUSION: NCT increased the eligibility for BCS from 40.4% to 62.6% in a clinical setting. This benefit is similar to that observed in other clinical trials.