218P - Oncological impact of re-excision for positive margin status after breast conserving surgery in invasive breast cancer

Abstract

BackgroundPositive margin of breast-conserving surgery (BCS) is well known to be a risk factor for ipsilateral breast tumor recurrence (IBTR). SSO/ASTRO guidelines defined ink on invasive cancer or DCIS as positive margin and recommend considering doing re-excision of the site of positive margin. However, whether re-excision can reduce IBTR has not been fully investigated yet. The aim of this study was to retrospectively assess the oncological impact of re-excision for positive margin status after BCS in invasive breast cancer. MethodsThe subjects were 196 invasive breast cancer patients who underwent BCS, and who were found to have positive margin. Of the 196 patients, 55 underwent re-excision after initial BCS (group A), and 139 did not (group B). We analyzed IBTR free survival in each group and evaluated the predictors for IBTR and overall survival (OS) using Cox proportional hazards modeling. ResultsOf the 196 patients, 188 (96%) underwent adjuvant radiotherapy and 24 of 55 re-excision (43%) identified residual disease. There was no significant difference in 10-year IBTR free survival between group A and group B (94.4% versus 93.8%; P=0.58). In a multivariate analysis, re-excision was not associated with IBTR and OS, while younger age, lack of adjuvant radiotherapy, and invasive component of margin status were independent predictors of IBTR. ConclusionsIn our retrospective study, re-excision for positive margin after initial BCS in invasive breast cancer does not contribute to prevent IBTR and may not translate into improved OS. Further treatment should be considered when patient was younger and margin status was invasive component. Legal entity responsible for the studyKenjiro Jimbo. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.