High rates of modifiable cancer risk factors present in Western HIV-positive patients

The prevalence of potentially modifiable risk factors for some cancers is “extraordinarily high” among people with HIV, according to results of a meta-analysis published in AIDS. An examination of studies conducted in western countries in the era of modern antiretroviral treatment showed that over half of people with HIV smoked, over two-thirds of HIV-positive men who have sex with men (MSM) had anal infection with human papillomavirus (HPV) types associated with a high risk of cancer and that over a quarter of people with HIV were also infected with hepatitis C virus (HCV). These rates were well in excess of those seen in the general US population.

“To our knowledge, this is the first comprehensive meta-analysis of the prevalence of cancer risk factors among PLWHA [people living with HIV/AIDS],” write the authors. “About half of PLWHA were current smokers, a prevalence 2.5 times higher than in US adults.” The investigators describe the reported rates of HPV infection in people with HIV as “distressingly high”.

Cancer is firmly established as a leading cause of death for people with HIV in the US and other western countries (Canada, western Europe and Australia). In addition, the incidence of both AIDS-defining and non-AIDS-defining cancers is significantly higher in people with HIV compared to individuals in the general population.

Immune damage caused by untreated HIV infection is a likely explanation for the excess cancer rates seen in people living with HIV. Modifiable risk factors are also thought to have an important role.

A team of US investigators wanted to determine the prevalence of several potentially modifiable risks for cancer among people with HIV. They undertook a meta-analysis of studies involving people who received HIV care in western countries that reported on the prevalence of smoking, hazardous alcohol consumption, HPV infection, hepatitis C virus (HCV) infection, hepatitis B virus (HBV) infection and overweight/obesity. The prevalence of each risk factor was compared to that observed in the general US population. To be eligible, studies had to report on people who received care between 2000 and 2013 and the research was required to have been published between 2011 and 2013.

A PubMed search identified 113 eligible studies. In terms of study design, 49 were prospective cohorts, ten were retrospective cohorts, 46 were cross-sectional studies, two were case-controlled and six had an experimental design. The median number of people in each study was 388. Most were conducted in the US (59) or western Europe (46). Approximately two-thirds of patients were male, their average age was 44 years and 84% were taking antiretroviral therapy.

Smoking prevalence was reported in 45 publications; overall 54% of people with HIV were current smokers, approximately 2.5 times higher than the estimate for the general US population (20 to 23%).

Data on hazardous alcohol consumption were provided in 26 studies. This risk factor was present in 24% of people with HIV. The prevalence in the general US population is estimated at between 5 and 15%.

Eighteen studies reported on the proportion of people with HIV who were overweight or obese. Just under one-third (32%), of people were classed as overweight, a similar proportion (34%) observed in the general US population. However, the rate of obesity among people with HIV was lower than the estimate for the wider population (17% and 34%, respectively).

Information about the proportion of HIV-positive people with HPV infection was provided in 18 publications. Cervical high-risk HPV infection was present in 46% of women. The comparative figure for the general US population is 29%. Some 16% of people with HIV had oral HPV infection, compared to a rate of 4% in the general population. Over two-thirds (68%) of HIV-positive MSM had anal high-risk HPV infection. No comparative data for the general population were available.

HCV prevalence data were reported in 63 studies. Their results showed that 26% of HIV-infected individuals had chronic HCV infection, the comparable figure for the general US population being 0.9%.

Twenty-six publications reported on HBV infection status. Overall, 5% of people with HIV were also living with HBV. The HBV prevalence rate in the general population was estimated at just 0.3%.

“Interventions to reduce the high prevalence of smoking and oncogenic virus infections among PLWHA can play a critical role in reducing the high cancer burden,” conclude the researchers. “Epidemiological studies to estimate the population attributable percent for various cancer types due to cancer risk factors among PLWHA would help guide both research and practice.”