Epidemiology of Genitoanal HPV Infections and Associated Cancer

The etiology of cervical cancer has been successfully linked to the persistent infection with a few strains of Human Papillomavirus (HPV). The association is consistent worldwide and causality has been generally accepted, on the basis of molecular epidemiological studies, including prevalence surveys, case control studies, cohort studies to the cervical intraepithelial neoplasia (CIN) 2/3 level, and screening studies. More recently, HPV vaccination trials have consistently concluded that vaccination against HPV types 16 and 18 could virtually eliminate the occurrence of HPV 16/18-related CIN 2/3. Current research is now claiming HPV causality for other genital cancers in females and males, anal cancer, and a fraction of cancers of the oral cavity and oropharyngeal regions. Worldwide, HPV prevalence in women with normal cytology at any given point in time is approximately 10%. HPV 16 is consistently the most common viral type and HPV 18 the second with some minor regional differences. Sexual behavioral patterns across age groups and populations are central to the description of the HPV circulation and of the risk of infection. The epidemiology of HPV infections in men and its relation to male cancer is being actively investigated, with several outstanding issues in relation to sampling and testing methods.