Time to extend the indication for sentinel node biopsy in vulvar cancer? Results from a prospective nationwide Swedish study.

objectiveTo 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.

methodsBetween 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.

resultsIn 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.

conclusionIn 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.