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 (99ᵐTc-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-99ᵐTc-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-99ᵐTc 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.