Abstract P2-14-18: Oncological Outcomes of Nipple-Sparing Mastectomy after Neoadjuvant Chemotherapy
Authors: RABINOVICH IRIS , Nissen Leonardo P. , Soares Isabela C. , Fornazari Alessandra C. , Spautz Cleverton C. , Sebastião Ana Paula M. , URBAN CICERO A. , Anselmi Karina F. , Schunemann Eduardo , Kuroda Flavia , Doria Maira T. , Andrade Ana Clea S. , Lima Rubens S. 
Published: March 2023

Introduction: Surgery is the mainstay treatment of breast cancer and has been improving in aesthetic outcomes even in locally advanced disease. Radical mastectomies are being replaced by less aggressive surgeries with immediate breast reconstruction. Nipple-Sparing Mastectomy (NSM) preserves Nipple Areolar Complex (NAC) along with the entire breast skin envelope and is associated with better aesthetic results and quality of life, improving patient satisfaction. Since NSM is a relatively recent technique and few studies have shown the feasibility of NSM after neoadjuvant chemotherapy (NACT), there are some concerns and controversies about its oncological safety, especially, with regard to the NAC recurrence due to the remaining tissue in the retroareolar area. This study compares the long-term oncological outcomes and correlated factors of NSM and skin-sparing mastectomy (SSM) after NACT.

Methods: After approval by the institution’s ethics committee a retrospective review was conducted to identify all patients who underwent NSM and SSM with immediate breast reconstruction after NACT between January 2011 and December 2018 at Centro de Doenças da Mama- Breast Unit Hospital Nossa Senhora das Graças. Metastatic disease, recurrent breast cancer, and other types of mastectomies were excluded. Clinicopathological and survival data, as well as recurrence events were collected from the electronic medical records. NSM was offered to the patients without involvement of the NAC and skin clinically and on imaging. All patients underwent ultrasonography, mammography and breast MRI in the preoperative period, as well as breast MRI after NACT. The decision to undergo adjuvant radiotherapy was determined by the treating radiation oncologists according to NCCN and ASTRO recommendation. A propensity score match was used to reduce the effect of selection bias on type of surgery and create well-balanced groups. The covariates included for matching were: anatomical stage, radiotherapy and molecular subtype.

Results: A total of 188 patients underwent mastectomy in this period, 134 NSM and 54 SSM. After propensity score matching, 92 patients in the NSM group were matched to the 54 patients in the SSM group. The median follow up time was 44,7 months to NSM and 40,3 months to NSM. The characteristics of patients included in both groups after propensity score matching are described in Table 1. NAC recurrence was observed in 5 (5.4%) of 92 NSM patients, and median time of recurrence was 24.2 (11.7- 40.1) months. Ki67 showed a significant relationship with relapse in the NAC. The distance from the tumor to the NAC and other clinicopathologic variables were not correlated with NAC recurrence (Table 2). There were no significative differences between the groups in locorregional recurrence (p=0.102), distant metastasis (p=0.223) and death (p=0.610) (Table 3).

Conclusion: In this matched control study, there was no difference in oncological outcomes in patients submitted to NSM and SSM after NACT, suggesting NSM with immediate breast reconstruction is a feasible option in this setting.

Table 1. Characteristics of patients treated with NSM and SSM after propensity score matching *Student’s t test for independent samples or non-parametric Mann-Whitney test (quantitative variables); Fisher’s exact test or chi square test (categorical variables); p&lt;0.05

Table 2. Correlation between clinicopathologic variables and recurrence in the NAC *Fine and Gray Regression Model including death as a competitive risk and Wald test, p&lt;0.05

Table 3. Oncological outcomes in NSM and SSM groups *Model Fine & Gray and Wald test, p&lt;0,05 **Cox Regression Model and Wald test, p&lt;0.05 *** Log-rank test, p&lt;0,05

Citation Format: IRIS RABINOVICH, Leonardo P. Nissen, Isabela C. Soares, Alessandra C. Fornazari, Cleverton C. Spautz, Ana Paula M. Sebastião, CICERO A. URBAN, Karina F. Anselmi, Eduardo Schunemann, Flavia Kuroda, Maira T. Doria, Ana Clea S. Andrade, Rubens S. Lima. Oncological Outcomes of Nipple-Sparing Mastectomy after Neoadjuvant Chemotherapy [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 P2-14-18.