RESUMEN
PURPOSE: A positive margin after breast conserving surgery has consistently been shown to be a significant predictor for ipsilateral breast tumor recurrence. Currently, there is no standard for intraoperative margin assessment during lumpectomy, and up to 20% of cases result in positive margins. MarginProbe is a device that provides real-time evaluation of lumpectomy margins during surgery. The aim of this study was to evaluate the impact of MarginProbe as an adjunct to standard operating procedure (SOP). METHODS: Patients diagnosed with breast cancer scheduled for breast conserving surgery were consented for intraoperative use of MarginProbe. Shaved margins were excised based on margin assessment using the surgeon's SOP which included specimen radiography and gross pathologic examination, and feedback from the device. The primary endpoint was re-excision rate. Secondary endpoints included sensitivity, specificity, false-positive and negative rates. RESULTS: Of the 60 breast cancers, initial histologically close/positive margins were identified in 18 patients (30%). The re-excision rate in the overall cohort was 6.6%, compared to a historical re-excision rate of 8.6% (p < 0.01). Based on 360 measurement sites, MarginProbe demonstrated a sensitivity of 67% and specificity of 60%, with a positive predictive value of 16%, and of negative predictive value of 94%, which was similar to the accuracy of SOP. CONCLUSIONS: MarginProbe performs equally as well as specimen radiography and gross pathologic examination. In this setting where the baseline re-excision rate was low, the use of MarginProbe as an adjunct to SOP resulted in a small 2% absolute reduction in re-excision rate.