Introduction/Background To evaluate the accuracy of sentinel lymph node (SLN) detection using indocyanine green (ICG) compared to the gold standard of lymphoscintigraphy with technetium 99m (99mTc) in women affected by early-stage vulvar cancer in high-level experienced oncological setting.

Methodology Thirty-seven patients with vulvar squamous carcinoma stage IB were enrolled in a prospective observational study at the European Institute of Oncology, Milan, from December 2014 to April 2023. Patients underwent to standard SLN procedure using 99mTc the day before surgery. In addition, a total dose of 2 ml ICG solution (1.25 mg/ml) was intradermally administered before surgery at the same sites as the 99mTc injections. All SNLs were identified and sent to histological examination.

Results Eighteen patients had a midline tumor and nineteen a unilateral tumor (12 left and 9 right), therefore 57 groins were investigated. Mean body mass index (BMI) was 24.9, mean age was 65.4 years. Overall, SLN detection rate (DR) was 94.6% and 89.2% by ICG and 99mTc, respectively. Considering laterality and for patients, ICG showed a SLN DR of 94.4%, 100% and 85.7% for midline, left and right tumours. 99mTc demostrated a lower DR for midline tumours (83.3%) but not statistically impactful. For groins, ICG and 99mTc had a overall DR of 94% and 92%, divided in 94% vs 100% in midline, 100% vs 83 in left and 86% vs 86 in right . BMI was significantly associated with SLN detection discordance between ICG and 99mTc ( p=0.03) as well as surgical diagnostic excision ( p=0.04).

Conclusion Our data show that ICG tracer is feasible and safe. It has a high accuracy to identify SLN, better or at least comparable to 99mTC detection rate. Moreover, a combined technique (ICG + 99mTC) could be suggested in patients with midline tumors and high body mass index.

Disclosures Discosures for E. Preti added COI.