Anal Pap smears are performed in a similar fashion to cervical Pap smears, with the area being swabbed to collect cells, which are then examined under a microscope. They can detect abnormal cells (anal dysplasia), but the anal Pap smear may be less likely to correlate with the degree of anal dysplasia that can be seen on a biopsy of an anal lesion revealed by high resolution anoscopy (HRA). Because such specificity is lacking, and there haven’t been any evidence-based clinical trials to evaluate anal cancer screening methods in preventing anal cancer, many clinicians feel that anal Pap smears should not be done at this time. However, I agree with other experts in the field who have proposed yearly anal Pap smears for all HIV-positive individuals. If the anal Pap is normal, continued annual screening is suggested. Experts also recommend anal Pap smears every one to two years for other high-risk groups and if normal, continued screening every two or three years. If any abnormal cells are detected, HRA with biopsy is recommended. However, these guidelines may be limited by the need to train a greater number of clinicians in performing HRAs and biopsies. It is also important for these screening tests to be administered in a non-hospital setting, to maximize patient compliance with screening and follow-up.
High-risk HPV subtypes, especially 16 and 18, are associated with cervical, anal, penile, vulvar, vaginal, and oral cancers. Cervical cancer is an AIDS-defining malignancy and its incidence has been decreasing with aggressive screening and treatment of pre-cancerous lesions or higher grade cervical dysplasia. Cervical cancer affected 35-40 per 100,000 women in the general population prior to cervical cancer screening and treatment and has now decreased to about 8-10 per 100,000.