New tracer compared with traditional radioactive tracer for sentinel lymph node biopsy in breast cancer: The FLUORO trial

This is a non-randomised trial. All participants who have consented to participate will undergo sentinel lymph node biopsy using both indocyanine green and technetium-99mm techniques. At the time of surgery after anaesthesia and immediately before the operation, 0.5 mL of Infracyanine® 25mg/10mL (SERB, Paris, France) will be injected subdermally into the peri-areolar area of the breast. Movement of ICG in the lymph ducts will be facilitated by manual massage. Operating room lights will be turned off to avoid any potential interference of ambient light with detection of ICG fluorescence. Fluorescence of ICG will be immediately elicited and detected by the near-infrared (NIR) camera (SPY-PHI, Novadaq Technologies Inc., Mississauga, Canada). The lymphatic drainage will be visualized in real time on a monitor. The fluorescence will be followed from the site of injection towards the axilla, and where the fluorescence disappears into the axilla, an incision is made to commence the biopsy. The fluorescent lymphatic channels will then be dissected and followed to the first ICG avid lymph node with assistance from the NIR camera. The lymphatic channels will be clipped and ligated to avoid ICG leakage into the dissection field which can distort visualisation of lymphatic anatomy. Fluorescent lymph nodes (ICG-positive) will then be localized and excised. These excised ICG-positive nodes will then be tested for radioactivity using a gamma-detecting probe and classified as hot (99mTc-positive) or cold (99mTc-negative). Sentinel lymph node removal will continue until no residual fluorescence is visible in the axilla. Finally, the axilla will be inspected with the gamma-detecting probe to determine whether any radioactivity is left. If there is significant residual radioactivity the hot spot (considered to be a 99mTc-positive SLN) will be removed and examined. The number of sentinel nodes (ICG-positive, 99mTc-positive, or both) removed from each patient will be documented. With regard to radioactivity, a SLN will be defined as any node that when measured ex vivo will have a gamma count ratio, compared to the background axilla, of 10:1. All SLNs will be sent for histopathology analysis. Sentinel lymph nodes will be compared to identify concordance among those identified as fluorescent, radioactive, and both. The total number of SLNs identified by ICG, 99mTc, or both, will be recorded. The approximate duration of the procedure will be 1 hour if it is combined with a wide-local excision. The duration of the procedure will be 1.5 hours if it is combined with a mastectomy.