A comparison of ICG-NIR with blue dye and technetium for the detection of sentinel lymph nodes in vulvar cancer

The sentinel lymph node (SLN) procedure for vulva cancer is a safe alternative to a radical inguino-femoral lymphadenectomy (IFLN) for small unifocal tumours. SLN evaluation through biopsy and ultra-staging has helped gynaecological oncology surgeons improve operative morbidity with no cost to oncologic safety. Established techniques for groin SLN detection and excision in vulvar cancer use 99mTc-nanocolloid radiotracer and blue dye (BD) for identification of the SLN. Indocyanine green (ICG)-near infrared (ICG-NIR) techniques for SLN mapping have proven utility in other gynaecological cancer sites and is gaining interest as a technique for SLN mapping in vulvar cancer METHODS: Fifty consecutive patients with unifocal vulvar squamous cell cancers of <40 mm lateral diameter and with depth of invasion > 1 mm underwent SLN mapping and excision using a combination of 99mTc-nanocolloid, BD and ICG. SLN detection results were recorded on a per-patient and per-groin basis. The success rates SLN for detection by individual tracer substance or combinations of tracer were determined by presence of one or more tracer, detectable in the SLN specimen.92% of patients had a successful SLN procedure. The per-groin detection rate was 84%. All successfully mapped SLN were identified with the combination of ICG-NIR and 99mTc-nanocolloid compared to 69% with BD 99mTc-nanocolloid. Success rates for the SLN procedure were not dependent on prior excision of the primary lesion or operator experience.Incorporation of ICG-NIR into standard SLN mapping protocols may allow for the abandonment of routine use of BD and its poor side effect profile.