Abstract P3-12-08: Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience
Authors: ZH Hopkins, J Frandsen, KE Poruk, J Agarwal, MM Poppe
Journal: Cancer Research (2016)

Abstract Introduction Nipple sparing (NSM) and skin sparing (SSM) mastectomies are gaining popularity. These procedures leave breast tissue at the skin/breast interface with the intent to better cosmesis. However, the impact of NSM versus SSM on risk of local recurrence in the remaining breast tissue is not well characterized, nor is the effect of post mastectomy radiotherapy (PMRT) in these patients. Methods A single institution retrospective study was conducted on women treated with NSM or SSM from 2005 to 2011 with follow up through 2015. Chest wall and chest wall or axillary recurrence were assessed. Factors associated with recurrence were examined. Kaplan Meier estimates and Cox proportional hazards models were used to analyze chest wall recurrence (CWR) and chest wall or axillary recurrence (CWAR), with CWAR as the primary outcome variable. Results This analysis identified 181 women who underwent a SSM (n=103, 58 (56%) with PMRT) or NSM (n=78, 35 (45%) with PMRT). Women undergoing SSM were older (56.0 ± 13.6 years, mean ± SD) than NSM (44.6 ± 11.3, p &amp;lt;0.0001) while follow-up times were similar (4.91 ± 0.43 and 5.43 ± 0.27 respectively, p = 0.15). Women undergoing PMRT were younger (49.2 ± 13.6 vs 53.1 ± 13.9 years, p = 0.008) but more likely to present with lymphovascular space invasion (LVSI)(42% vs 16%, p = 0.0003 by Chi-square), and were more likely to receive chemotherapy (83% vs 47%, p &amp;lt;0.0001). The majority of women (62%) in the group not receiving PMRT had stage I disease, and 79% were node negative. For those undergoing PMRT, 83% were stage II or III, and 69% were node positive (p &amp;lt;0.0001 for both differences). Despite the higher apparent risk of the PMRT group, the total number of chest wall or axillary recurrences was similar (8 in PMRT, 6 in no PMRT). Event-free survival for CWAR at 5 years was 92% for PMRT and 96% for no PMRT (p=0.42) and at 7.5 years, 85% and 84% respectively (p=0.42). In univariate Cox regression among all patients, age was the strongest predictor of CWAR (HR = 1.103 per year of age, 95% CI 1.053-1.154, p&amp;lt;0.0001). CWAR occurred in 2.6 % of NSM patients as compared with 11.8% of SSM patients (p=0.025 by Fisher's exact test). SSM versus NSM was associated with increased hazzard for CWAR with HR = 4.6 (95% CI 1.03-21, p=0.046) on univariate analysis. However, this apparent risk became non-significant (HR = 2.24, 95% CI 0.48 – 10.5) with adjustment for age. Other variables associated with CWAR on univariate analysis included receipt of chemotherapy (HR = 0.28, 0.09-0.86, p=0.027) and estrogen receptor positive status (HR = 0.34, 0.12-0.98, p=0.046) but these also became non-significant with adjustment for age. In multivariate Cox regression analysis, use of PMRT was associated with a non-significant higher risk of CWAR (HR = 1.45, 0.33-6.4, p=0.63 ) adjusting for age, LVSI, mastectomy type, stage, and ER status. Conclusions The risk of a chest wall or axillary recurrence for early stage breast cancer after a SSM or NSM appears to be low at five years. Radiation can likely be omitted in this group. Furthermore, despite presenting with more advanced disease, women who underwent PMRT experienced excellent locoregional control. Further research is needed on this topic. Citation Format: Hopkins ZH, Frandsen J, Poruk KE, Agarwal J, Poppe MM. Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-08.