Diagnostic accuracy of intraoperative macroscopic margin evaluation in breast-conserving surgery

Intraoperative margin assessment techniques have been developed to reduce positive margin rates after breast-conserving surgery (BCS). These techniques show limited diagnostic accuracy, particularly after neoadjuvant systemic therapy (NST). The study aim was to evaluate the diagnostic accuracy of intraoperative macroscopic pathological margin evaluation (IMPME).

This was a retrospective study including patients with invasive breast cancer (BC) who underwent BCS between 2015 and 2017. A tumor-margin distance ≤1 mm was considered positive at IMPME. Diagnostic accuracy, sensitivity (Se), specificity (Sp) and negative predictive value (NPV) of IMPME were calculated according to the timing of surgery. The gold standard was margin status at final pathology.

A total of 698 BC tumors, were included, 561 in the upfront BCS group (UBCS) and 137 in the delayed (after NST) BCS group (DBCS). According to IMPME, 25.1% and 27.7% of BC tumors had positive margins in the UBCS and DBCS groups, respectively. Final pathological examination showed positive margins for 5.9% in the UBCS group and 8.8% in the DBCS group. Diagnostic accuracy, Se, Sp, and NPV were, respectively, 82.5%, 83.1%, 82.5%, and 97.4%, for the UBCS group and 81.7%, 76%, 84%, and 93.9%, respectively, for the DBCS group. IMPME-guided re-excision reduced secondary surgeries rates by 74% in the UBCS group, and by 50% in the DBCS group.

IMPME can enhance correlations between the margin status of the main breast surgical specimen and final pathology. With its high NPV rates, IMPME can predict negative final margins and avoid additional intraoperative re-excisions.