Abstract P2-14-02: Surgical options of the breast and clinical outcomes in breast cancer patients after neoadjuvant chemotherapy: a single-center retrospective study
Authors: Sang Yuting , Chen Jiajian , Yang Benlong , Hao Shuang , Huang Xiaoyan , Liu Guangyu , Shao Zhimin , Wu Jiong 
Published: March 2023

Abstract
Background: Neoadjuvant chemotherapy (NAC) has evolved significantly and has been widely accepted for downstaging disease in early-stage and locally advanced breast cancer patients. Since the optimal surgical intervention of the breast for patients receiving NAC remains controversial, we aim to investigate the survival outcome of patients treated with different surgical management.
Methods: Patients with invasive breast cancer that underwent NAC in Fudan University Shanghai Cancer Center from January 2010 to June 2019 were involved in this study. Based on surgical intervention of the breast following NAC, patients were divided into mastectomy and breast conservation groups. To be specific, the mastectomy group involved patients who received mastectomy alone or mastectomy plus immediate breast reconstruction (M+IBR), while the breast conservation group evolved patients who underwent conventional breast-conserving surgery (CBCS) and oncoplastic surgery (OPS). Surgical interventions were performed by breast surgeons. Propensity scores matching was utilized for group matching.
Results: A total of 2080 patients were enrolled in this study. Among them, 1819 (87.5%) patients were categorized as mastectomy group, and 261 (12.5%) patients were classed as breast conservation group. In the mastectomy group, mastectomy alone and M+IBR accounted for 82.5% (1715/2080) and 5% (104/2080) patients respectively. As for breast conservation, 170 (8.2%) and 91 (4.4%) patients were treated with CBCS and OPS after NAC. Over 9-years of research, the proportion of breast conservation steadily increased in patients after NAC. Notably, the percentage of patients undergoing OPS increased from 0.43 % to 7.60 % throughout the 9 years. Moreover, increasing rate of M+IBR was also observed in the study cohort, whereas fewer patients opted for mastectomy alone as surgical intervention after NAC. Compared with mastectomy group, patients underwent BCS showed younger age (P &lt; 0.001), as well as higher proportion of normal BMI (P = 0.022), pre-menopausal status (P &lt; 0.001), and triple-negative breast cancer (P &lt; 0.008). Additionally, patients with tumors of advanced clinical T stage (P &lt; 0.001) and TNM stage (P = 0.002) were more often to be treated with mastectomy (Table 1). After propensity score matching, 460 patients were matched successfully (Table 2). Compared with the mastectomy group, significant benefits in overall survival (Hazard ratio 0.51, [95% confidence interval: 0.27-0.96]; p=0.044) and disease-free survival (Hazard ratio 0.62, [95% confidence interval: 0.39-0.99]; p&lt;0.05) were observed in the breast conservation group (Table 3A and 3B). Moreover, there was no statistical difference in locoregional recurrence among the surgical groups (Table 3C).
Conclusions: Tumor biology can significantly impact the surgical decision in patients administrated with NAC. Breast conservation was a safe alternative for mastectomy in the NAC setting without compromising survival outcomes.
Table 1. Clinicopathologic characteristics of patients in mastectomy and breast conservation groups.
Table 2. Balanced statistics of patients receiving mastectomy and breast conservation after propensity score matching.
Table 3. Survival analysis between matched cohort of patients receiving mastectomy (n=230), breast-conserving therapy (n=230).
Citation Format: Yuting Sang, Jiajian Chen, Benlong Yang, Shuang Hao, Xiaoyan Huang, Guangyu Liu, Zhimin Shao, Jiong Wu. Surgical options of the breast and clinical outcomes in breast cancer patients after neoadjuvant chemotherapy: a single-center retrospective study. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-02.