Efficacy of Intraoperative Widening of Surgical Resection Margins for Non-Palpable Breast Cancer: An Analysis of 771 Breast-Conserving Surgeries

Background: The aim of the implementation of preoperative marking procedures in non-palpable breast cancer is to obtain a successful excision of the intended lesion with tumor-free resection margins while removing as little as possible of the surrounding healthy breast tissue to better preserve cosmetic integrity. Based on the intraoperative X-ray of the tumor specimen, intraoperative widening of selected surgical resection margins (IWSM) can be performed to decrease the positive margin rate. This study aims to evaluate the role of IWSM in breast-conserving surgery. Methods: All patients undergoing guidewire localized conservative surgery for non-palpable breast cancers were considered for the study. Patients, tumor characteristics, and pathological findings were collected. Tumor specimens undergoing intraoperative X-ray were considered for the analysis. The number of IWSM specimens, the IWSM specimens containing tumor cells at final histology, and the volume of IWSM specimens were calculated. Results: Data from 771 tumorectomies for non-palpable breast cancer performed between 2017 and 2023 at the Centro di Senologia della Svizzera Italiana (CSSI) were collected. A total of 751 tumorectomies with intraoperative X-ray assessment of the margin’s status were included. In 461/751 cases (61.4%), at least one IWSM specimen was obtained. At the final histopathology, in 354/461 IWSM specimens (76.8%), no tumor cells were reported, while they were reported in 107/461 (23.2%). Of these, 89/107 (83.2%) had overall negative margins, while 18/107 (16.8%) presented involved margins at the final histopathology. In 323/461 (70.1%) IWSM specimens, the pathological report provided three dimensions useful for volume calculation. The mean volume of these specimens was 9 ± 15 cm3. Conclusions: IWSM can help increase the efficacy of tumorectomies for non-palpable breast cancer lesions. However, in the majority of cases, healthy breast tissue is removed as well. Tumor and patient characteristics may help in the selection of cases for which IWSM reduces the positive margin rate and the number of unnecessary procedures.