Symposium on Human Papillomavirus (HPV) Infection
The natural history of HPV infection was reviewed as part of a symposium on viral co-infections with HIV. Data from the New York Cervical Disease Study, which has followed both HIV-positive and HIV-negative women since 1991, was presented. They observed that HIV-positive women are more likely to be infected with HPV (60% vs. 35% in HIV-negative women) and are more likely to be infected with the subtypes of HPV that can cause cervical cancer (types 16 and 18). They also noted that lower CD4-cell counts increased women's risk of pre-cancerous cervical disease. Being HIV-positive also appears to increase a woman's risk for cervical cancer. In New York, while there was no overall increase in cervical cancer from 1983 to 91, in HIV-positive women there was a 2- to 3-fold increased incidence.
In men, the relationship between pre-cancerous changes in the anal canal and invasive cancer is less clear. While HIV-positive men have a higher rate of HPV infection and abnormal cells in the anal canal, the incidence of invasive anal cancer in HIV-positive men who have sex with men (MSM) does not appear to be higher than the cancer risk of HIV-negative MSM. In two studies, HIV-positive men did show a higher incidence of abnormal findings on anal pap smears (University of California at San Francisco -- 28% vs. 8%; University of Washington -- 53% vs. 22%). It is still unclear why the increased risk of cancer in HPV- and HIV-positive women does not show up in HPV- and HIV-positive men.
In both women and men, it appears that improvements in the immune system may help control, or even reverse, some of the abnormal changes seen in the cervix and anal canal. But there is very little data to fully address this issue in the "post-HAART era." Hopefully, in the next year or two, the answer to these questions will become clearer.
This information could then be used to make decisions about whether to screen HIV-positive men with anal pap smears, and about the preferred treatment of abnormal anal canal changes. While treatment for women with abnormal cervical pap smears is currently standardized, there is still no similar consensus on how best to treat men with abnormal anal pap smears.