Abstract
OBJECTIVE: To assess detection rates and negative predictive values of sentinel node biopsy in vulvar squamous cell carcinoma with tumors ≥4 cm, multifocal tumors, and in locally recurrent disease. METHODS: Between December 2019 and December 2022, patients with vulvar squamous cell carcinoma with tumors ≥4 cm (group 1), multifocal tumors (group 2), or a first local recurrence without or with previous groin treatment (groups 3 and 4, respectively) were included in a prospective, nationwide multicenter interventional pilot study. The participants underwent a sentinel node biopsy followed by inguinofemoral lymph node dissection. Detection rates, negative predictive values, the proportion of micrometastases, and isolated tumor cells were determined separately for each group. RESULTS: In all, 64 women were included, 36 women in group 1 (56%), and 17 women in group 2 (27%). Due to the small number and heterogeneity of the 11 women in groups 3 and 4, they were excluded from further analyses. In groups 1 and 2, 25 women (47%) were diagnosed with node-positive disease, and in 16 women (64%) only in the sentinel nodes. The detection rates varied between 94.1-100% per patient and 84.1-85.3% per groin. No false-negative sentinel nodes were identified, giving a negative predictive value of 100% for group 1 (95% CI 91.2% to 100%) and for group 2 (95% CI 83.9% to 100%). Of the node-positive patients, 32% had micrometastasis or isolated tumor cells only. One third of the metastases were detected by ultrastaging. In 27% of the non-mapping groins, metastases were found in the lymphadenectomy specimen, and in 75% the metastases showed extranodal growth. CONCLUSION: In this small cohort of patients, we provide further data that may widen the indication of the sentinel node technique to women with tumors ≥4 cm and multifocal tumors. TRIAL REGISTRATION NUMBER: NCT04147780.