New Insights into the Epidemiology of Vulvar Cancer: Systematic Literature Review for an Update of Incidence and Risk Factors

Abstract

The aim of this review was an update of vulvar cancer incidence rates and trends and of all known and putative risk factors for the disease. The most recent incidence data were sought from official sources (WHO Cancer Incidence in Five Continents). To obtain an estimate of time trends in some areas, we compared data from Cancer Incidence in Five Continents with the few available studies that measured incidence using comparable methods. With respect to risk factors, a systematic PubMed search identified 1585 relevant articles published between 1980 and 2021. Abstracts and full texts were screened. Sixty-nine eligible original cohort and case-control studies were selected. Information was extracted using a PRISMA predesigned form. Nineteen risk factors, or risk factor categories, were investigated by two or more original studies. Solitary, unreplicated studies addressed the putative role of eight more factors. Recent advances have provided further evidence supporting the carcinogenic model centred on human papillomavirus infection with different defects of the immune function. Conversely, the model centred on the role of vulvar lichen sclerosus and the often associated differentiated vulvar intraepithelial neoplasia has continued to be epidemiologically understudied. More research on the association between these two conditions and vulvar cancer is a priority.