Epidemiology and Natural History of Anal HPV Infection and ASIL and Cancer in the General Population

Abstract

Carcinoma of the anal canal is an increasingly prevalent problem that has been causally associated with infection by oncogenic strains of the human papillomavirus. Concurrent infection with HPV and the human immunodeficiency virus is the most significant risk factor; however, among HIV-negative men and women, risk factors include receptive anal intercourse, the presence of condyloma, multiplicity of HPV serotype infection, injection drug abuse, and the presence of cervical, vulvar, or penile neoplasia. Although there is limited data on the natural history of anal HPV infection and the progression to anal cancer, a number of epidemiologic and associative studies have demonstrated that anal squamous intraepithelial lesions represent an intermediate step in the progression to cancer. This relationship is analogous to the pathogenesis of invasive cervical carcinoma that is similarly asociated with cervical squamous intraepithelial lesions. Further study may elucidate the factors responsible for the pattern of regression or persistence after HPV infection.