Worldwide human papillomavirus genotype attribution in over 2000 cases of intraepithelial and invasive lesions of the vulva

Abstract

Background: Human papillomavirus (HPV) contribution in vulvar intraepithelial lesions (VIN) and invasive vulvar cancer (IVC) is not clearly established. This study provides novel data on HPV markers in a large series of VIN and IVC lesions. Methods: Histologically confirmed VIN and IVC from 39 countries were assembled at the Catalan Institute of Oncology (ICO). HPV-DNA detection was done by polymerase chain reaction using SPF-10 broad-spectrum primers and genotyping by reverse hybridisation line probe assay (LiPA25) (version 1). IVC cases were tested for p16INK4a by immunohistochemistry (CINtec histology kit, ROCHE). An IVC was considered HPV driven if both HPV-DNA and p16INK4a overexpression were observed simultaneously. Data analyses included algorithms allocating multiple infections to calculate type-specific contribution and logistic regression models to estimate adjusted prevalence (AP) and its 95% confidence intervals (CI). Results: Of 2296 cases, 587 were VIN and 1709 IVC. HPV-DNA was detected in 86.7% and 28.6% of the cases respectively. Amongst IVC cases, 25.1% were both HPV-DNA and p16INK4a positive. IVC cases were largely keratinising squamous cell carcinoma (KSCC) (N = 1234). Overall prevalence of HPV related IVC cases was highest in younger women for any histological subtype. SCC with warty or basaloid features (SCC_WB) (N = 326) were more likely to be HPV and p16INK4a positive (AP = 69.5%, CI = 63.6–74.8) versus KSCC (AP = 11.5%, CI = 9.7–13.5). HPV 16 was the commonest type (72.5%) followed by HPV 33 (6.5%) and HPV 18 (4.6%). Enrichment from VIN to IVC was significantly high for HPV 45 (8.5-fold).