Abstract P1-11-13: Re-excision rate in breast conservation surgery after neoadjuvant chemotherapy

Abstract

Abstract Background : The goal of neoadjuvant chemotherapy is to reduce tumor size and convert mastectomy to breast-conservation surgery (BCS). In response to neoadjuvant chemotherapy, the regression rate and pattern of breast cancer is variable. And the re-excision rate to secure negative resection margin is reported limitedly in this case. The purpose of this study was to compare the re-excision rate and BCS success rate of patients who received and who did not received neoadjuvant chemotherapy. Method : In this retrospective cohort study, between January 2009 and December 2012, total 256 women were included who had clinical T2 breast cancer and were planed to receive BCS as initial operation or neoadjuvant chemotherapy. Fifty-nine patients of them received neoadjuvant chemotherapy. Clinical data were collected including age, preoperative or initial clinical tumor size, mammographic microcalcifications, ultrasound multifocality and axillary nodal status, retrospectively. In the resected specimen from BCS, we reviewed the pathologic tumor size, multifocality, histologic type, hormone receptor and Her-2-neu status, ki67, DCIS and EIC component. The re-excision rate and BCS success rate were investigated. Univariate analysis and regression model were used for identify clinicopathologic factors associated with re-excision. To reduce the effect of selection bias, propensity score matching-based anaylsis was also performed. Results : Of the 256 patients, 178 patients (90.4%, 178/197) received BCS finally in neoadjuvant group and 56 patients (94.9%, 56/59) in non-neoadjuvant group (p=0.406). There was no statistical difference in the re-excision rate between two groups (35.6% (21/59) in neoadjuvant group vs 34.0% (67/197) in non-neoadjuvant group, p=0.946). In propensity-matched cohorts (N=118), the re-excision rate was same in two groups (35.6% (21/59) in neoadjuvant group vs 35.6% (21/59) in non-neoadjuvant group, p=1.000). BCS success rate was higher in neoadjuvant group(94.9% 56/59) than non-neoadjuvant group (86.4%(51/59)), but there was no statistical difference (p=0.205). In this cohorts, clinicopathologic factors associated with re-excision were pathologic multifocality (OR=4.56, p=0.0142), high ki67 (≥50%) (OR=0.7, p=0.0243) and DCIS component (OR=2.67, p=0.0261) in logistic regression model. Conclusion: This study showed neoadjuvant chemotherapy could increase the BCS success rate but could not decrease the re-excision rate. The re-excision rate is more associated with pathologic finding rather than effect of neoadjuvant chemotherapy. Citation Format: Song JH, Park JY, Choi JE, Bae YK, Lee SJ. Re-excision rate in breast conservation surgery after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-11-13.