Sentinel Lymphadenectomy in Vulvar Cancer Using Near-Infrared Fluorescence From Indocyanine Green Compared With Technetium 99m Nanocolloid

Objective Nowadays, sentinel diagnostic is performed using technetium 99m (Tc-99m) nanocolloid as a radioactive marker and sometimes patent blue. In the last years, indocyanine green has been evaluated for sentinel diagnostic in different tumor entities. Indocyanine green is a fluorescent molecule that emits a light signal in the near-infrared band after excitation. Our study aimed to evaluate indocyanine green compared with the criterion-standard Tc-99m-nanocolloid. Methods We included patients with primary, unifocal vulvar cancer of less than 4 cm with clinically node-negative groins in this prospective trial. Sentinel diagnostic was carried out using Tc-99m-nanocolloid, indocyanine green, and patent blue. We examined each groin for light signals from the near-infrared band, for radioactivity, and for blue staining. A sentinel lymph node was defined as a Tc-99m-nanocolloid-positive lymph node. All sentinel lymph nodes and all additional blue or fluorescent lymph nodes were excised and tested and then sent for histologic examination. Results In all, 27 patients were included in whom we found 91 sentinel lymph nodes in 52 groins. All these lymph nodes were positive for indocyanine green, also giving a sensitivity of 100% (95% confidence interval [CI], 96.0%-100%) compared with Tc-99m-nanocolloid. Eight additional lymph nodes showed indocyanine green fluorescence but no Tc-99m positivity, so that the positive predictive value was 91.9% (95% confidence interval, 84.6%-96.5%). In 1 patient, a false-negative sentinel missed by all 3 modalities was found. Conclusions Our results show that indocyanine green is a promising approach for inguinal sentinel identification in vulvar cancer with a similar sensitivity as radioactive Tc-99m-nanocolloid and worth to be evaluated in further studies.