Intraoperative ultrasound margin evaluation as a tool to reduce positive superficial margins in nipple and skin sparing mastectomy in breast cancer patients

Background: Intraoperative ultrasound (IOUS) guided conservative surgery has been shown to reduce rates of positive margins in breast cancer. The aim of the study is to evaluate the feasibility of using IOUS to assess superficial/anterior margins in nipple and skin sparing mastectomy (NSM/SSM) and its impact on reducing rates of positive margins.Methods: This prospective study includes all breast cancer patients who had an indication for NSM/SSM at our Institution. Superficial margin width was measured by IOUS before surgery and the area marked on the skin. Same measurement was performed afterwards in the mastectomy specimen. Any superficial margin < 5 mm was re-excised intraoperatively following the mark on the skin.Results: Fifty-nine patients were included, 47 patients (79.7%) underwent NSM, and 12 patients (20.3%) a SSM. Of the 59 patients, 23 (38.98%) had margins >= 5 mm and 36 patients (61.02%) had margins of <5 mm. Of the 36 patients with superficial margins <5 mm, 20 had margins <2 mm, and 6 of them had intraoperative involved superficial margins in final pathology. However, after IOUS-guided re-excision, final pathology showed no involved margins. A 2 mm margin was set as the cut-off point for performing an intraoperative re-excision. IOUS guided re-excisions for intraoperative margins <= 2 mm significantly reduced the risk of close/positive margins in final pathology, p < 0.0001.Conclusion: The results showed that IOUS margin evaluation significantly reduced the rate of superficial positive margins in NSM/SSM. It is feasible and effective and may avoid challenging reoperations and/or additional radiation therapy for positive margins.