Re-Operation Rate for Breast Conserving Surgery Using Confocal Histolog Scanner for Intraoperative Margin Assessment-SHIELD Study.

: In breast conserving surgery (BCS), 15-40% of patients must undergo a second surgery (re-operation) due to post-surgical cancer-positive margins. Efficient intraoperative assessment of lumpectomy margins can reduce this rate. Classical methods like specimen radiography and ultrasound have limitations. The SHIELD study was conducted to prospectively quantify the reduction of the re-operation rate when the Histolog Scanner (HLS) confocal microscope is intraoperatively used by surgeons for the margin assessment. : 50 patients undergoing BCS were enrolled and analyzed. Lumpectomy margins were intraoperatively assessed by surgeons with the HLS in addition to standard-of-care techniques. Detected positive margins triggered the excision of additional recuts during the same surgery. Subsequent re-operation and detection rates were compared to historical data and pathology gold standards, respectively. : The study population included 32% of patients with pure invasive cancer(s), 18% with pure DCIS and 50% with invasive cancer(s) mixed with DCIS. The overall mean age was 63.56. All population features were statistically similar to the historical control ( > 0.1). Notably, 80.95% sensitivity and 99.53% specificity for breast cancer detection at the margin were intraoperatively achieved by the surgeons using the HLS. The re-operation rate in SHIELD was 10% (5/50) while the historical control was 30% (12/40) corresponding to a 67% reduction ( = 0.016). Notably, 17/21 positive margins were intraoperatively identified with the HLS while 4/21 were detected with standard-of-care techniques. : The intraoperative use of the Histolog Scanner confocal microscope provides a significant increase in detection rates of lumpectomy positive margins resulting in a substantial reduction in the re-operation rate, while preserving specimen integrity without impact on histopathology assessment.