Screening, Surveillance, and Treatment of Anal Intraepithelial Neoplasia.

The prevalence of anal intraepithelial neoplasia has been increasing, especially in high-risk patients, including men who have sex with men, human immunodeficiency virus positive patients, and those who are immunosuppressed. Several studies with long-term follow-up have suggested that rate of progression from high-grade squamous intraepithelial lesions to invasive anal cancer is ∼ 5%. This number is considerably higher for those at high risk. Anal cytology has been used to attempt to screen high-risk patients for disease; however, it has been shown to have very little correlation to actual histology. Patients with lesions should undergo history and physical exam including digital rectal exam and standard anoscopy. High-resolution anoscopy can be considered as well, although it is of questionable time and cost-effectiveness. Nonoperative treatments include expectant surveillance and topical imiquimod or 5-fluorouracil. Operative therapies include wide local excision and targeted ablation with electrocautery, infrared coagulation, or cryotherapy. Recurrence rates remain high regardless of treatment delivered and surveillance is paramount, although optimal surveillance regimens have yet to be established.