Accuracy of ultrasound-guided breast-conserving surgery in the determination of adequate surgical margins.

The goal of this study was to assess the size of the ultrasound-measured margin associated with an adequate surgical margin during breast-conserving surgery (BCS). The study was designed as a prospective cohort study. Patients with primary invasive breast cancer undergoing BCS were included. The ultrasound-measured surgical margins were compared with the pathological margins. 147 patients were eligible for analysis. 21 (14.3 %) patients had close or positive resection margins and 13 (8.8 %) underwent a second operation. Small excision volume, multifocality, postmenopausal status, high grade tumor-associated intraductal component, and invasion of lymph vessels and lymph nodes were associated with increased risk of positive excision margins. In the study cohort, 882 Ultrasonography (US) margins were measured and a good correlation to the pathological margins was observed. Overestimation of the US-measured margins relative to the pathological margins was increased with younger age, premenopausal status, and intraductal component. The estimated positive and negative predictive values, sensitivity and specificity were 81.0, 96.2, 48.4, and 99.1 %, respectively. We found that a sonographically estimated margin of ≥ 4 mm was associated with an adequate pathological margin of ≥ 1 mm in 100 % of tumors that did not have a high grade intraductal component. However, this was not applicable for tumor-associated high grade intraductal component where a US margin of 14 mm was associated with clear pathological margins in 100 % of cases. Intraoperative ultrasonography is a safe and feasible method to obtain clear surgical margins by BCS.