The cumulative rates of anal, colorectal, and liver cancers are increasing among HIV-positive patients, mainly because in the antiretroviral era they are living long enough for these malignancies to develop, according to a report published online Oct. 5 in Annals of Internal Medicine.
Certain cancers are known to be more common among HIV-infected than among noninfected adults, but it has been uncertain whether this is because of a true increase in incidence or simply to these patients’ greater longevity in recent years, said Michael J. Silverberg, Ph.D., a research scientist at Kaiser Permanente Division of Research, Oakland Calif., and his associates.
Dr. Michael J. Silverberg
The investigators analyzed data from 16 U.S. and Canadian cohorts participating in the North American Cohort Collaboration on Research and Design to compare time trends in cancer incidence between 86,620 adults with HIV and 196,987 demographically similar control subjects without HIV. These study participants were followed from 1996 to 2009 for the development of nine cancers: Kaposi’s sarcoma, non-Hodgkin’s lymphoma, lung cancer, anal cancer, colorectal cancer, liver cancer, oral cavity/pharyngeal cancer, Hodgkin’s lymphoma, and melanoma. As expected, the incidences of all of these malignancies were higher among patients with HIV than among control subjects.
The cumulative incidence of anal, colorectal, and liver cancer increased over time among HIV-positive but not among HIV-negative adults. This was attributed primarily to the declining death rate among HIV-positive patients, which “presumably allowed more persons to survive long enough to have long-term exposure to human papillomavirus infection” in the case of anal cancer and to hepatitis B and C virus infection in the case of liver cancer. In the case of colorectal cancer, rates steadily declined in the control subjects as they have in the general population due to increased screening and earlier detection of lesions with malignant potential. “We hypothesize that this disparity in colorectal cancer trends may be because persons with HIV lag behind” in getting screened for colorectal cancer, Dr. Silverberg and his associates said (Ann Intern Med. 2015 Oct 5. doi: 10.7326/M14-2768).
Kaposi’s sarcoma, non-Hodgkin’s lymphoma, and lung cancer “remain of great concern” among HIV-positive adults, and the investigators calculated that each of these malignancies carry high lifetime (to age 75 years) risks of 1 in 25 in this patient population. “Efforts need to be intensified to promote early, sustained [antiretroviral therapy], the only known approach to prevention of these and possibly other cancer types linked to immunosuppression or inflammation,” they noted.
Time trends in the rates of oral/pharyngeal cancer, Hodgkin’s lymphoma, and melanoma did not differ significantly between patients with HIV and control subjects.
This study was supported by the National Institutes of Health, the Centers for Disease Control and Prevention, the Agency for Healthcare Research and Quality, the Health Resources and Services Administration, the Canadian Institutes of Health Research, the Ontario ministry of Health and Long-Term Care, the government of Alberta, and the National Cancer Institute. Dr. Silverberg reported receiving grants from Pfizer and Merck; his associates reported ties to Gilead Sciences, Merck, GlaxoSmithKline, Genosea, and Nordique.