Introduction/Background Vulvar intraepithelial neoplasia’s (VIN) comprise a heterogeneous disease entity and have an ambiguous vulvar squamous cancer (VSCC) risk. Human Papillomavirus (HPV) associated VIN accounts for more than 90% of all high-grade VIN, while HPV-induced vulvar squamous cell carcinomas (VSCC) only account for 25% of all VSCCs. This study aimed to investigate the incidence of VIN and the subsequent VSCC risk in relation to age, type of VIN, and presence of lichen sclerosus (LS) and human papillomavirus (HPV), to optimize monitoring and clinical care of women with VIN.

Methodology The PALGA database, the Dutch Pathology Registry, enabled us to identify a large, historical cohort of women with VIN diagnosed between 1991 and 2011 with long term follow-up, up to 2018. Data on type of VIN, presence of lichen sclerosus (LS), HPV and VSCC development were collected.

Results In our cohort, 1,148 women were diagnosed with VIN between 1991 and 2011. The incidence of VIN increased with from 2.7 to 4.5 per 100,000 woman-years (67%). Although most women diagnosed with VIN were between 35 and 55 years of age, the incidence rate of VIN peaked in women ≥ 70 years. In women with VIN, the cumulative VSCC risk was 15.7% after 27.4 years. This cumulative cancer risk was increased in women with dVIN (66.7%) compared to women with other types of high grade VIN (15.1%, p<0.001). Consistently, VSCC risk was higher in elderly women with VIN, in women with LS-related VIN and in women with HPV-negative VIN.

Conclusion Our findings on a large cohort of women with VIN with long-term follow-up support the different routes in vulvar carcinogenesis. Because of the increased cancer risk in women with VIN diagnosed at a higher age and in women with HPV negative or LS associated VIN, intensified clinical care in these groups is needed.

Disclosure Nothing to disclose.