Abstract P1-16-09: Magnetic sentinel node and occult lesion localization in breast cancer: Initial results of the MagSNOLL trial

Trial registration: ISRCTN: 68689512 MREC No: 13/LO/0636 UKCRN ID: 14979 INTRODUCTION: One-third of breast cancers diagnosed are non-palpable. These breast cancers require localization-guided surgery and axillary staging using sentinel lymph node biopsy (SLNB). We present our experience of the first 20 patients undergoing a novel technique of magnetic-guided lesion localization and concurrent SLNB, avoiding the need for wire-guided localization and radioisotopes. MATERIALS AND METHODS: Co-localization of the primary tumour and sentinel lymph nodes (SLNs) using a novel magnetic technique was initially undertaken on a protocol-driven predefined minimum of 10 patients with palpable breast cancers to assess the feasibility of the magnetic tracer to safely localize at the point of injection and concurrently drain to the lymphatics. In order to confirm proof of principle, the subsequent 20 patients with non-palpable breast cancers were analysed. An ultrasound-guided intra-tumoral injection of magnetic tracer was performed (0.5 mL Sienna+, Endomagnetics Ltd, UK). Once successful lesion localization was confirmed (peak magnetometer counts retained at the site of injection), the technique was undertaken in patients with non-palpable breast cancers awaiting wide local excision and SLNB. All patients underwent SLNB with the magnetic and combined technique (radioisotope and Patent Blue Dye). RESULTS: A total of 33 patients were recruited and 1 patient excluded due to breach of the trial protocol. This left a remainder of 32 patients for consideration, of which 12 patients (1 bilateral) possessed palpable breast cancer and 20 patients non-palpable breast cancer. Peak magnetometer counts were retained at the site of injection in all palpable (n=13) and non-palpable (n=20) breast cancers. Re-excisions (second operations) for involved margins were performed in 2 patients with non-palpable breast cancers (10%). The mean volume of excised specimens was 49 cm3 (SD 30.6). The SLN identification rate for the magnetic technique alone was 84% (28/33) overall and 85% (17/20) for non-palpable lesions. For the combined technique (radioisotope and blue dye) the SLN identification rate was 97% (32/33) overall and 100% (20/20) for non-palpable lesions. When the magnetic technique is combined with blue dye, the SLN identification rate overall was 97% (32/33) and for non-palpable breast cancers was 95% (19/20). The mean number of sentinel nodes excised was 1.75 versus 2.05 for the magnetic and combined techniques respectively. CONCLUSION: Magnetic lesion localization and concurrent SLNB is a feasible technique. Further optimisation and validation of this technique, in a larger trial, is required. Citation Format: Muneer Ahmed, Ashutosh Kothari, Hisham Hamed, Sumit Goyal, Tibor Kovacs, Anand David Purushotham, Bauke Anninga, Phillippa Young, Julie Scudder, Sarah McWililliams, Sarah Pinder, Quentin Pankhurst, Ian Monnypenny, Michael Douek. Magnetic sentinel node and occult lesion localization in breast cancer: Initial results of the MagSNOLL trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-16-09.