HIV Linked to Rising Rates of Anal Cancer among U.S. MenAn increase in the incidence of anal cancer among men in the United States during recent decades may have been driven in part by the HIV epidemic that occurred during the same period, a new study suggests. The results, published in the Journal of the National Cancer Institute on October 4, provide a framework for understanding the rising rates of anal cancer in men and could help guide efforts to prevent the disease.
Dr. Meredith S. Shiels of NCI’s Division of Cancer Epidemiology and Genetics and her colleagues estimated that between 2001 and 2005, more than 28 percent of anal cancer cases among men were associated with HIV infection, whereas only 1.2 percent of anal cancer cases in women were associated with HIV.
Although anal cancer is rare in the United States, the incidence has been increasing since 1940. Between 1980 and 2005, the rate of anal cancer in men in the general population rose 3.4 percent per year. The authors noted that half of this increase was due to cases of anal cancer occurring in men who were infected with HIV.
Men who have sex with men are at high risk of both HIV infection and anal cancer. Human papillomavirus (HPV) infections of anal tissue and anal precancerous lesions, which increase the risk of anal cancer, are common in this group. But the extent to which the incidence of anal cancer among people infected with HIV has affected incidence rates in the general population was not clear.
To explore this question, the study authors used data from the HIV/AIDS Cancer Match Study. They looked at the number of people with anal cancer infected with HIV in 17 U.S. states and metropolitan areas.
“HIV-infected cases have had a substantial impact on trends in anal cancer rates among men in the U.S.,” said Dr. Shiels. She noted that rates among women have also increased, but the cause remains unclear. “Efforts to reduce the risk of anal cancer in HIV-infected men could have a sizeable impact on anal cancer rates at the general population level,” she concluded.
This research was supported in part by NCI's Intramural Research Program.
Further reading: "HPV Vaccine Study in Costa Rica Yields Insights on Cancer Prevention"