SAN FRANCISCO—A look at the epidemiology of anal cancer shows the need for thorough anal exams, particularly in patients of either sex with HIV disease, Joel M. Palefsky, M.D., said at a meeting on HIV management sponsored by the University of California, San Francisco.
Before the HIV epidemic, reported rates of anal cancer among men who have sex with men (MSM) were as high as 35/100,000, about the same as the cervical cancer rate in women before universal screening. Data now suggest that MSM with HIV disease have anal cancer rates as high as 100/100,000, or about 10 times the rate of cervical cancer in screened women, which has declined to about 8/100,000, said Dr. Palefsky of the university.
Visual inspection of the anal opening is not enough, although it should not be dispensed with. It can, for example, show the plaques of Bowen's disease. Two centimeters inside the anal canal is a transformation zone where the rectal columnar epithelium meets the anal squamous epithelium. This is where most disease occurs.
After visual inspection, the next step is an anal Pap smear, which must be done without lubricant. Moisten a Dacron (not cotton) swab with tap water or saline and insert it past the anal-rectal junction as far as it will go. As it's pulled out, it will capture a good sample of cells from the transformation zone, which can then be examined cytologically and tested for human papilloma virus (HPV). Virtually everyone with HIV disease—women as well as men—will have an HPV infection, some with as many as 10 virus types.
The next step is a digital rectal exam, which is a good cancer-screening tool, Dr. Palefsky said. Put a lubed finger into the anal canal and feel for masses.
The next step is anoscopy with a standard plastic anoscope. Cancerous and precancerous lesions in the anus appear similar to what one would see in the cervix.
Dr. Palefsky cautioned against dismissing standard-seeming warts, especially in individuals with HIV disease. These patients often have high-grade disease mixed in with the warts. “We recommend sampling, through biopsy, lesions of different appearance when patients have multiple lesions.”