Incidence and Risk Factors for Recurrence and Progression of HPV-Independent Vulvar Intraepithelial Neoplasia

ObjectivesHuman papillomavirus (HPV)-independent vulvar intraepithelial neoplasia (VIN) is a rare yet aggressive precursor lesion of vulvar cancer. Our objectives were to estimate its long-term incidence, the risk of recurrent disease and progression to vulvar cancer, and risk factors thereof.Materials and MethodsPatients with HPV-independent VIN between 1991 and 2019 in a selected region were identified from the Dutch Nationwide Pathology Databank (Palga). Data were collected from the pathology reports. Crude and European age-standardized incidence rates were calculated for 10-year periods. Kaplan-Meier analyses were performed to determine the cumulative recurrence and cancer incidence, followed by Cox regression analyses to identify associated risk factors.ResultsA total of 114 patients were diagnosed with solitary HPV-independent VIN without prior or concurrent vulvar cancer. The European age-standardized incidence rate increased from 0.09 to 0.69 per 100,000 women-years between 1991-2010 and 2011-2019. A cumulative recurrence and cancer incidence of 29% and 46% were found after 8 and 13 years of follow-up, respectively. Nonradical surgery was identified as the only independent risk factor for recurrent HPV-independent VIN. Risk factors associated with progression to cancer were increasing age and a mutant p53 immunohistochemical staining pattern.ConclusionsThe incidence of detected HPV-independent VIN has substantially increased the last decade and the subsequent recurrence and vulvar cancer risks are high. Although HPV-independent VIN may present as a wide morphologic spectrum, surgical treatment should aim for negative resection margins followed by close surveillance, especially for p53 mutant lesions.