Impact of Standardized Intraoperative Ultrasound on Re-excision Rates in Breast-Conserving Surgery.

INTRODUCTION: The primary objective of breast-conserving surgery (BCS) is complete excision of the tumor with histologically negative margins (R0 resection). Intraoperative ultrasound (IOUS) has been shown to reduce re-excision rates (R1) for sonographically visible breast cancer. However, a standardized IOUS technique has not yet been established. This study aimed to evaluate whether standardization using the "Tübingen Ultrasound Ruler" can reduce R1 resection rates. PATIENTS AND METHODS: This retrospective study included 273 patients who underwent BCS between January 2020 and December 2023 for unilateral or bilateral ductal carcinoma in situ and/or invasive breast cancer, regardless of tumor biology, the presence of microcalcifications, or prior chemotherapy. All surgeries were performed by a single surgeon. Tumors were excised with a sonographically assessed margin of >10 mm in all directions. After specimen imaging, additional margin shavings were obtained when indicated. RESULTS: A total of 282 specimens were analyzed, with a mean specimen weight of 110.5 g. Considering the main resection specimen alone, the R1 rate was 18.8%. Targeted IOUS-guided shavings significantly reduced the R1 rate to 8.5%. Compared with the mean R1 rate of the average figures of OnkoZert-certified breast centers reported between 2020 and 2023 (12.34%), the use of the "Tübingen Ultrasound Ruler" in combination with specimen imaging was associated with a significantly lower R1 rate (p = 0.043). CONCLUSION: Standardization of the IOUS technique combined with imaging-guided targeted shavings makes it possible to achieve a low R1 rate (8.5%) in breast-conserving surgery.