Resection margins in ultrasound-guided breast-conserving surgery.

BACKGROUND: Few published studies have shown the benefits of intraoperative ultrasound in avoiding inadequate margins in breast-conserving surgery. The aim of this study is to quantify intraoperative ultrasound margin size and assess its relationship to tumor size, multifocality, palpability, histology, and presence of intraductal component.
METHODS: Patients with breast cancer undergoing breast-conserving surgery in whom the operating surgeon visualized the tumor by ultrasound were included. Ultrasound margins measured intraoperatively were prospectively recorded and compared with pathology margins.
RESULTS: Forty-five patients with 48 tumors were included. Twenty five patients (56%) had palpable tumors. Pathologic mean tumor size was 1.9 cm [95% confidence interval (CI) 1.6-2.2 cm, range 0.5-4.8 cm]. There was good correlation between closest margins recorded by ultrasound and pathology margins (r = 0.4674, P < 0.0008). Fourteen patients (31%) had margins re-excised intraoperatively, 12 of them in the direction of the closest pathological margin. Three patients (7%), all of whom had intraoperative re-excision, had a second operation for involved margins without residual cancer on pathological examination of the reoperative specimens. Ultrasound margins ≥0.5 cm achieved adequate pathology margins of ≥0.2 cm in 95% of margins. Overestimation of pathology margins by ultrasound measurement was significantly affected by multifocality (P = 0.0473). Tumor size, palpability, invasive lobular histology, and presence of ductal carcinoma in situ (DCIS) did not cause significant overestimation of pathology margins by ultrasound.
CONCLUSIONS: Intraoperative ultrasound may help maintain a low level of reoperation after breast-conserving surgery. Ultrasound margins <0.5 cm should be re-excised intraoperatively. Reliability of ultrasound in predicting the closest pathology margins was diminished in patients with multifocal tumors.