Abstract P4-14-08: Intraoperative ultrasound guidance for excision of non-palpable breast cancer

Background: The effectiveness of intraoperative ultrasound (IOUS) for preoperative localization of non-palpable breast cancers within the operation theatre has not been studied extensively. In this prospective cohort study, we compared margin status, re-excision rate and excised volume of IOUS to guidewire localization (GWL). Methods: A total of 258 consecutive patients with non-palpable invasive breast cancer underwent breast conserving surgery between 1999–2010. GWL was performed in 138 (54%) and IOUS in 120 (46%) patients. Tumour dimensions, resection volume, margin status and re-excision rates were compared by means of multivariate regression analysis. Calculated resection ratios, i.e. indicating the amount of excess tissue resection, were calculated by dividing the total resection volume by the optimal resection volume (the tumor diameter plus a 1.0 cm margin) and compared between the groups. Results: The groups were similar in terms of age, histological subtype and presence of DCIS. Lesions in the IOUS group were larger (1.24 vs. 0.98 cm), while lesions in the GWL group consisted more often of microcalcifications only (19% vs. 3%). Tumour free resection margins were obtained in more than 93% of patients (93.5% with GWL vs. 93.3% with IOUS, P = .958) and re-excision was performed in 11.0% of patients undergoing GWL and 12.5% of patients undergoing IOUS (P = .684). In both groups, resection volumes were similar, but IOUS led to more optimal tissue resection (calculated resection ratio 4.33 vs 3.30, P = .018). After adjustment for tumor diameter, radiological findings and presence of DCIS, the difference in calculated resection volumes was no longer significant. Conclusion: For localization of non-palpable breast cancer, IOUS is a reliable alternative to GWL, as it achieves similar results in terms of complete tumour removal, re-excision rate and excised volume. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-14-08.