Human Papillomavirus‒Positive and ‒Negative Vulvar Squamous Cell Carcinoma Are Biologically but Not Clinically Distinct.

Vulvar squamous cell carcinoma pathogenesis is traditionally defined by the presence or absence of human papillomavirus (HPV), but the definition of these groups and their molecular characteristics remain ambiguous across studies. In this study, we present a retrospective cohort analysis of 36 patients with invasive vulvar squamous cell carcinoma where HPV status was determined using RNA in situ hybridization and PCR. Clinical annotation, p16 immunohistochemistry, PD-L1 immunohistochemistry, HPV16 circular E7 RNA detection, and RNA sequencing of the cases were performed. A combination of in situ hybridization and PCR identified 20 cases (55.6%) as HPV positive. HPV status did not impact overall survival (hazard ratio: 1.36, 95% confidence interval = 0.307-6.037, P = 0.6857) or progression-free survival (hazard ratio: 1.12, 95% confidence interval = 0.388-3.22, P = 0.8367), and no significant clinical differences were found between the groups. PD-L1 expression did not correlate with HPV status, but increased expression of PD-L1 correlated with worse overall survival. Transcriptomic analyses (n = 23) revealed distinct groups, defined by HPV status, with multiple differentially expressed genes previously implicated in HPV-induced cancers. HPV-positive tumors showed higher global expression of endogenous circular RNAs, including several circular RNAs that have previously been implicated in the pathogenesis of other cancers.