US-guided BCS is superior to palpation-guided excision in predicting the closest margins, obtaining clear surgical margins, and reducing re-operations.

!Purpose: The aim of this study was to investigate the value of intraoperative ultrasound in breastconserving operations and to compare it with standard procedures. Methods: For this purpose 307 women with palpable breast cancers and 116 patients with nonpalpable breast cancers were compared retrospectively. In the group with palpable breast cancers 177 patients were treated by US-guided operations and 130 patients underwent palpationguided breast-conserving operations. As primary outcomes, the resection margins and the rate of re-operations were evaluated. Results: With regard to disease-free resection margins, intraoperative ultrasound was significantly superior to palpation alone. In the group of patients in whom the tumours were extirpated with the help of palpation, R1 resections were observed almost twice as often (16.9 %) as in the USguided group (8.5%). In the group with non-palpable breast cancers, intraoperative ultrasound was employed in 61 patients. As a control, 43 cases were evaluated in whom the breast-conserving operation was performed after wire marking. In this group US-guided tumour removal proved to be superior to that after wire marking for tumours that did not exhibit any intraductal components. Otherwise the redo resection rate was reduced by use of ultrasound. Furthermore, the surgeon was able by means of intraoperative ultrasound to identify "problematic" margins and to excise them in the same sitting. Conclusions: The US-guided, breast-conserving operations led to a lower rate of R1 resections and redo operations in comparison to operations with palpation alone or those after wire marking. Ergebnisse: Im Hinblick auf freie Resektionsrän-der war die intraoperative Sonografie der alleinigen Palpation signifikant überlegen. In der Gruppe der Patientinnen, deren Tumor mithilfe der Palpation exzidiert worden ist, wurde eine R1-Resektion fast doppelt so häufig beobachtet (16,9 %) wie in der US-gestützten (8,5 %). In der Gruppe der nicht palpablen Mammakarzinome wurde die intraoperative Sonografie bei 61 Patientinnen angewendet. Als Kontrolle wurden 43 Fälle evaluiert, bei denen eine brusterhaltende Operation nach einer Drahtmarkierung durchgeführt wurde. In dieser Gruppe war die US-gestützte Tumorektomie der Tumorexzision nach Drahtmarkierung, für Tumore, die keine intraduktale Komponenten aufwiesen, überlegen. Sonst wurde die Nachresektionsrate durch die Sonografie reduziert. Zusätzlich war der Operateur in der Lage durch die Verwendung der intraoperativen Sonografie die "problematischen" Ränder besser zu identifizieren und in der gleichen Sitzung zu resezieren. Zusammenfassung