Anal Intraepithelial Neoplasia.

Anal squamous cell cancer (SCC) is a relatively uncommon cancer in the United States. Anal SCC has long been associated with human immunodeficiency virus (HIV) positivity and/or men who have sex with men. The incidence of anal SCC has been increasing in both genders regardless of HIV status. Few clinicians are aware that white women, when not controlling for gender and sexual preference together, have the highest incidence of anal SCC. Anal intraepithelial neoplasia (AIN), dysplastic cells of the anal canal due to human papilloma virus infection, is believed to be the precursor to anal SCC. A vaccination has been approved by the Federal Drug Administration (FDA) for the prevention of high-risk human papilloma virus infections in presexually active girls and boys. Currently, there are no consensus guidelines for AIN screening, treatment or follow-up. Although anal SCC is treatable when caught early, treatment is often associated with significant morbidity. The purpose of this paper is to raise awareness of anal SCC and its precursor, AIN, in the non-HIV+ and non-MSM populations, and discuss means by which to decrease the incidence of anal SCC in all populations.