ICG-fluorescence Imaging for Intraoperative Breast Cancer Margins Evaluation: a Dose-timing Study

The majority of breast cancer (BC) patients are diagnosed with an early-stage disease and are good candidates for breast-conserving surgery (BCS). Achieving adequate margins of excision is the most important component of BCS. Currently intra-operative margin assessment (IOMA) techniques used for margins evaluation in BC, either histological or imagistic is not accurate enough to predict the margins status of breast resected tumours and to guide surgery. Fluorescence imaging (FI) using indocyanine green (ICG), a non-specific fluorophore, has also been reported to be a new, promising, non-invasive and relatively low cost technology to improving the accuracy of tumor detection during surgery in different clinical cancers, such as those of the liver, colon, ovaries, head and neck, lungs and breast. Furthermore ICG-FI can provide a real-time guidance during surgery and could establish corrects margins resection by improving the visual delineation between normal and tumoral tissues. Only two clinical experience of ICG-FI for evaluating surgical margins in BC was reported. The group of Keating reported the first one, in a pilot study of 12 patients, after ICG intravenous (IV) injection (5mg/kg) they found that there was residual fluorescence in the tumoral bed in 6 out of 12 patients, but none of these patients had positive margins at definitive pathology. Recently, the investigators have reported the utility of ICG-FI after intraoperative ICG IV injection of 0.25 mg/kg for intraoperative breast surgical margin assessment during BCS. In a study of 35 BC patients, the investigators observed that the sensitivity (Se), specificity (Sp), and negative predictive value (NPV), of ICG-FI to predict margin involvement on the breast operative specimens were 100%, 60% and 100% respectively. Several important technical points exist in the experimental and clinical use of ICG-FI. There is a great variability of the published data regarding the baseline characteristics of the ICG use, like dosage and timing of administration (perioperative vs delayed). Furthermore, the fluorescence imaging system is usually different. In this study, the investigators would like to emphasize and to get more precision about the optimal ICG doses and timing, which could increase the diagnostic accuracy of intraoperative ICG-FI for resection margins assessment during BCS, after intravenously ICG administration.