Extending eligibility criteria for sentinel lymph node biopsy in vulvar cancer: An update on the GroSNaPET study

Sentinel node biopsy (SNB) is the standard approach for nodal staging in clinically node-negative (cN0) patients with unifocal vulvar cancer ≤4 cm. Patients outside these criteria undergo lymphadenectomy, although many prove node-negative. The prospective GroSNaPET study evaluated SNB followed by lymphadenectomy in these patients. This report presents updated outcomes, long-term follow-up, and complication data.

This single-center prospective study included cN0 patients ineligible for standard SNB due to ≥1 of the following: tumor >4 cm, multifocality, prior excision or (chemo)radiotherapy, unilateral nodal involvement, or relapse. All patients underwent SNB followed by complete lymphadenectomy. Histopathology was the reference standard. Complications were graded by Clavien-Dindo system. Diagnostic accuracy and survival outcomes were assessed with standard methods.

Seventy-two patients (114 groins) were enrolled. The preoperative lymphoscintigraphic SNB identification rate was 94.7%. Among 265 sentinel nodes removed, 19 (7.2%) showed metastases, involving 16/108 groins (14.8%). Overall, 17/108 groins resulted metastatic. The proportion of false negatives over the entire study population was 0.9% (1/108), with a false negative rate of 5.9% (1/17). The negative predictive value was 98.9% and the diagnostic accuracy was 99.1%. Postoperative complications occurred in 70.8% cases, mainly lymphedema (19.7%) and lymphoceles (12%); 17% were Clavien-Dindo grade ≥ III. Median follow-up was 54.5 months; 22 recurrences (30.6%, including 3 inguinal) and 15 deaths (20.8%) were recorded. 5-year Disease Free Survival and Overall Survival were 65.6% and 82.7%.

SNB is accurate and safe beyond standard criteria. This study provides a robust comparison for GroSNaPET 2, which omits lymphadenectomy when SN is negative.