AB018. SOH23ABS_206. Analysis of involved anterior and posterior margins in breast cancer—should we cut it out?

Background: Breast conserving surgery (BCS) has made tremendous advancements in the realm of cancer management, however, decisions about re-excisions of close margins remains controversial. This stems from the ambiguity of various guidelines in defining a standard approach. The aim of this study is to investigate outcomes in patients who underwent re-excision of close anterior and posterior margins in a single institution. Primary objectives included local recurrence and survival outcomes (disease free and overall survival).

Methods: All patients undergoing wide local excisions, from January 2015 to December 2020, at University Hospital Limerick were retrospectively reviewed from a prospectively maintained clinical database. Variables collected on each patient include patient demographics, hormone receptor status, tumour grade & histology, margin status, neo-adjuvant & adjuvant therapies, disease free and overall survival. A close margin was defined as ≤2 mm.

Results: Overall, 50 patients were included in the preliminary analysis, with a mean age of 61 (±13). Of the 50 patients, 13 (26%) had close anterior margins and 14 (28%) had close posterior margins. For anterior margins, 8 patients (61.5%) underwent further re-excision of margins. Re-excision of posterior margins was carried out in 6 (42.3%). No patients were found to have any residual disease following re-excision.

Conclusions: From our preliminary analysis, we have found that the majority of involved anterior margins go on to have re-excision compared to posterior margins. No re-excision specimens had involved margins indicating adequate clearance in all cases. Data collection and further analysis of patients is ongoing.

Keywords: Breast cancer; breast conserving surgery; margins; re-excision; wide local excision (WLE)