190 Relationship Between Tumour Characteristics and Margin Involvement for Skin-Sparing vs Simple Mastectomy: A Single Institution Experience

Abstract

Abstract Aim Skin-sparing mastectomy (SSM) are increasingly performed to facilitate breast reconstruction. Published data shows varying rates of margin involvement with SSM. We reviewed the relationship between clinicopathological characteristics and margin involvement after SSM versus simple mastectomy (SM). Method Retrospective case-series of breast cancer patients who underwent SM between June 2021-2022 or SSM (Dec 2019-Mar 2022) in a single tertiary centre. Demographic and clinicopathological data were retrieved from Trust systems. Margin involvement was defined as <1mm. Student’s t-test and Chi-square test were used to compare continuous and categorical variables. Results Study included 156 patients (n = 59 vs 97 [SSM vs SM]). Patients undergoing SSM tend to be younger (mean age = 47 vs 63, p<0.001 [SSM vs SM]), less often had high grade disease (22% vs 38% G3, p = 0.04) and involved lymph nodes (19% vs 48%, p<0.001), more often had DCIS only (24% vs 15%, p<0.001). Mean tumour size was similar (40.6 vs 38.7mm, p = 0.32[SSM vs SM]) as well as receptor status (61% vs 61% ER+, p = 0.125; 10% vs 18% HER2+, p = 0.21; 12 vs 16% triple negative, p = 0.43 [SSM vs SM]). Both groups had similar tumour margin involvement (8.47% vs 6.19%, p = 0.588). Conclusions The SSM cohort tend to be younger, had lower incidence of nodal involvement and higher rates of DCIS. The SSM and SM cohort showed similar mean tumour size, receptor distribution and tumour margin involvement rates. With appropriate planning, SSM does not increase the likelihood of margin involvement.