Abstract P1-01-23: Magnetic Sentinel Lymph Node Detection for Breast Cancer

Abstract

Abstract Background The combined technique is the preferred technique for sentinel lymph node biopsy (SLNB) but blue dye and radioisotope both have significant drawbacks including poor pre-operative imaging, radiation exposure regulation, blue dye obscuring the surgical field and skin tattooing. We have developed a non-invasive non-radioactive method for SLNB using magnetic nanoparticles and a handheld magnetometer (SentiMag), and have previously demonstrated proof of principle in an ex-vivo pilot study. Materials and methods Patients with newly diagnosed breast cancer underwent SLNB following injection of patent blue dye (Guerbet, Paris), radioisotope and 2ml of superparamagnetic iron oxide (Endorem, Guerbet, Paris). Endorem was injected subcutaneously at the circumareolar aspect of the upper outer quadrant in the affected breast. Intraoperatively, the SLN was identified using a combination of blue staining, black staining and gamma probe. Nodes were considered to be SLNs if their count exceeded 1/10th of the highest ex-vivo gamma count for any lymph node in that patient. Ex-vivo, gamma and SentiMag counts were compared. Receiver-operator curves were used to identify the optimal detection count for SentiMag. Results Of 32 patients, 1 was excluded for technical failure of the device intra-operatively. In all patients 1 or more sentinel nodes were detected with the combined technique (31/31). In 26/31 (84%) patients the node was positive for superparamagnetic iron oxide. Receiver-operator curves demonstrated a SentiMag reading of 20 units or above which was the optimal cut-off for SLN detection (sensitivity 61.75% specificity 62.5%). Success by node and by patient of the combined technique and the SentiMag technique Discussion Sentinel node biopsy using magnetic nanoparticles is feasible and the optimal cut-off point for sentinel node detection is 20 units. Further evaluation is needed to identify optimal injection dose and time delay between injection and nodal harvest in order to improve sensitivity and specificity. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-23.