Feasibility of real-time near-infrared fluorescence tracer imaging in sentinel lymph node biopsy for vulvar cancer patients

Background Sentinel lymph node biopsy (SLNB) using technetium-99 m-labeled radiocolloid ( 99 ᵐTc-Nanocoll) and blue dye is the standard of care for early-stage vulvar cancer. Indocyanine green (ICG) has emerged as a complementary tracer; however, data on its efficacy and oncologic safety remains limited. We evaluated SLN detection using a hybrid ICG– 99 ᵐTc-Nanocoll and assessed groin recurrence and survival outcomes. Methods Patients with early-stage vulvar cancer undergoing SLNB were consecutively enrolled between February 2018 and August 2022. All patients underwent preoperative LSG-SPECT/CT followed by intraoperative fluorescence-guided SLNB. Detection rates, pathological findings, and adjuvant treatment were recorded. Recurrence Free Survival (RFS) and Cancer Specific Survival (CSS) were estimated using Kaplan–Meier analyses and Cox regression models adjusted for stage. Results A total of 113 patients (191 groins; 35 unilateral, 78 bilateral) were included. Preoperative LSG-SPECT/CT identified SLNs in 86.2% of groins (94.6% per patient). Intraoperatively, SLNs were identified in 92.1% of groins and 98.2% of patients, with ICG alone detecting SLNs in 11% of groins — predominantly in midline tumors. SLN metastases occurred in 26 patients (23%). After a median follow-up of 52 months (IQR 39–67), isolated groin recurrence occurred in 1.9% of SLN-negative groins (2 patients). Two-year RFS was 90.8%, with no significant difference between mapped and non-mapped patients. Two- and five-year CSS were 97.3% and 91.4%, respectively. Conclusions Hybrid ICG– 99 ᵐTc mapping is feasible, safe, and highly effective for SLNB in early-stage vulvar cancer, including midline tumors, identifying sentinel nodes missed on LSG-SPECT/CT and preserving oncologic safety with a low rate of groin recurrence.