Abstract P2-14-13: Propensity score matching for survival outcomes in breast cancer patients with nipple sparing mastectomy versus total mastectomy and breast-conserving surgery: a single-center retrospective study
Authors: Xiong Min , Hao Shuang , Chen Jiajian , Huang Xiaoyan , Liu Guangyu , Shao Zhimin , Wu Jiong 
Published: March 2023

Abstract
Objective: With the development of the diagnosis and treatment of breast cancer, the pattern of multidisciplinary treatment has resulted a new tendency of breast conserving surgery and reconstruction. Nipple sparing mastectomy (NSM) preserves the aesthetically important nipple-areolar complex, improved appearance satisfaction and quality of life of patients after mastectomy, and had similar oncologic outcomes compared with traditional mastectomy techniques. The primary guiding principles of NSM are oncologic safety. Some studies have demonstrated its oncologic safety while others have demonstrated recurrent risk increasing because of the nipple-areolar complex. We sought to assess the overall survival and disease-free survival of NSM compared with breast-conserving surgery (BCS) and total mastectomy (TM). Key words: nipple sparing mastectomy, breast-conserving surgery, total mastectomy, the overall survival, the disease-free survival Methods: This retrospective matched-cohort study was conducted patients accepted breast surgery between January 2007 and December 2017 in the Department of Breast Surgery of Fudan University Shanghai Cancer Center. Cancer stages were identified depending on the American Joint Committee on Cancer [AJCC] TNM staging system. The inclusion criteria included (1) female breast cancer, (2) histopathology confirmed invasive breast cancer without distant metastasis or local relapses, (3) had complete clinical and pathological T&N stages. The exclusion criteria included in situ carcinoma, phylloides tumor, recurrent or metastatic breast cancer and pregnancy. The primary outcome was the overall survival (OS), the secondary outcome was the disease-free survival (DFS). Statistical methods included Kaplan-Meier survival analysis and COX regression analysis, all of which were completed by SPSS 20.0. Results: A total of 2757 patients were evaluated for eligibility, of which 430 were included (86 NSM vs 172 BCS vs 172 TM), the median follow-up is 61.57 months. Clinical T&N stage and other factors of the above three operations were balanced and comparable after matching. COX regression analysis reported that pT (pT3 vs pT1, P=0.00, HR 16.051, 95%CI:3.822-67.409) and pN (pN2 vs pN0, P=0.00, HR 16.626, 95%CI:4.581-60.337) were related factors for OS, and pT (pT3 vs pT1, P=0.021, HR 6.619, 95%CI:1.331-32.927) and pN (pN2 vs pN0, P=0.000; HR 13.320, 95%CI:3.250-54.591) are independent predictive factor of OS. In addition, pN (pN2 vs pN0, P=0.013; HR 3.448, 95%CI:1.304-9.118) was a related factor for DFS. Among 94.19% patients of the NSM group underwent breast reconstruction, 70 underwent implant-based breast reconstruction, 8 underwent autogenous flaps reconstruction, and 3 patients chose latissimus dorsi flap combined with prosthesis immediate breast reconstruction. Only 4 of 172 patients underwent autogenous flaps reconstruction in TM, and 1 chose implant-based breast reconstruction. Kaplan-Meier survival analysis found that the 5-year OS of NSM group, TM group and BCS group were respectively 100%, 95.8% and 99.2%. The 5-year DFS of three operations were respectively 95.2%, 92.1%, 93.5%. Patients who underwent NSM had no difference compared with BCS or TM regarding the OS (P=0.875, HR 0.938, 95%CI:0.421-2.090) and the DFS (P=0.882, HR 0.967, 95%CI:0.623-1.502). Conclusions: Patients undergoing NSM are not disadvantaged in terms of the OS and the DFS compared with patients who underwent BCS or TM. Patients with NSM tend to opt for breast reconstruction to keep good shape and it has the same prognostic outcome as patients with TM or BCS.
Citation Format: Min Xiong, Shuang Hao, Jiajian Chen, Xiaoyan Huang, Guangyu Liu, Zhimin Shao, Jiong Wu. Propensity score matching for survival outcomes in breast cancer patients with nipple sparing mastectomy versus total mastectomy and breast-conserving surgery: 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 P2-14-13.