Screening for Anal Cancer Better Defined but More Study Is Needed
Cases of anal cancer are on the rise in people living with HIV. Part of this is due to more attention being paid to the condition and people with HIV living longer lives. Screening tools are being better defined yet there is controversy over screening recommendations by providers. A recent British study attempted to better define the role of anal Pap smears to screen for anal cancer, similar to the way in which cervical Paps are used to screen for cervical cancer. The study followed 395 HIV-negative and HIV-positive individuals.
More than 9 out of 10 were men, about half were white, and 3 in 4 were men who have sex with men. Three forms of tests were performed on each person: an anal Pap smear (where the doctor swabs an area of the anus to remove surface cells), an anoscopy (where a doctor uses a special microscope to look at the anus), and a biopsy (where the doctor scrapes away an area of the anus to remove surface cells).
The results showed that anal Pap smears accurately detected pre-cancerous skin cells about 70% of the time. The higher the grade of disease, the more likely Pap smears could detect these skin cells. They were also more accurate when there were more pre-cancerous cells present.
Anal Pap smears were also better able to find disease in HIV-positive than HIV-negative people (76% vs. 59%). In addition, anal Pap smears were more likely to find disease when CD4s were below 400, and when two or more areas were swabbed for cells (86%) as opposed to one or more (69%).
Although this is good news for detecting pre-cancerous anal cells earlier, using anal Pap smears still leaves room for errors. These findings still indicate that other tests may need to be used to confirm anal Pap results, such as anoscopy. Medical providers should be encouraged to screen for all cancers related to HIV especially as the population ages. People with HIV should discuss their risk for anal cancer and their screening options and seek out experts in the field if necessary.
For more information on HPV, read Project Inform's publication HPV and HIV disease. Another online resource for anal cancer is the UCSF Anal Neoplasia Study.