HISMAR: Intraoperative Margin Assessment Using the Histolog® Scanner to Reduce Reoperation in Breast-Conserving Surgery

Summary

This study evaluates whether systematic intraoperative margin assessment using the Histolog® Scanner - a confocal fluorescence microscopy device - reduces the need for reoperation after breast-conserving surgery (lumpectomy) in women with lobular carcinoma (ILC), ductal carcinoma in situ (DCIS), or invasive carcinoma with a DCIS component (NST+DCIS). After lumpectomy, the fresh specimen is imaged in real time by the surgeon using the Histolog® Scanner, which produces histological-quality images of the specimen surface without any tissue processing. This allows immediate assessment of surgical margins in the operating room, enabling the surgeon to perform additional tissue removal if needed before closing. Based on institutional data from 266 cases at CHVR (2021-2024), the current reoperation rate in this population is 11.3%. The study tests whether systematic use of the Histolog® Scanner in addition to standard care reduces this rate by 50% or more (to ≤5.6%). A total of 228 patients will be enrolled prospectively at the Centre Hospitalier du Valais Romand (CHVR), Sion, Switzerland. The reoperation decision is made by the multidisciplinary tumour board based on final histopathology results, independently of the intraoperative findings.