A method to evaluate the use of fluorescent tracers to determine tumour margins during breast cancer surgery is reported in a small clinical trial in Nature Communications this week. The results show that the fluorescent tracer, bavacizumab-800CW, is safe and allows for significantly improved detection of tumour margins in patients with breast cancer.

During tumour removal, surgeons rely on visual inspection and palpation (a method of feeling with the fingers or hands during a physical examination) to detect tumour margins, which is an imprecise methodology. Fluorescent tracers allow targeting of tumour cells and are being tested in clinical trials, but standardized methods to determine the efficacy of a fluorescent tracer are lacking. In addition, current methods do not readily allow intraoperative monitoring, and require, for example, time-consuming processing of tissue sections, or techniques such as computerised tomography scanning and magnetic resonance imaging, which cannot be used in real-time during surgery.

Marjory Koller, Gooitzen van Dam and colleagues present the results of a clinical dose escalation trial to evaluate the efficacy of the fluorescent tracer bavacizumab-800CW in 26 patients during breast cancer surgery. The method is designed to fit existing workflows in the operating theatre and to allow the detection of tumour margins in real time.

The findings show that fluorescence imaging is safe, and resulted in an 88% increase in the intraoperative detection rate of tumour involved surgical margins. Further studies will be required to determine if this technique decreases the number of tumour positive margins (where cancer cells are present in the outer edge of the tissue that was removed) during breast-conserving surgery, and the re-operation rate following surgery.