Co-infection with HCV increases cancer risk for people with HIV

People with HIV and hepatitis C virus (HCV) co-infection have an increased risk of non-AIDS-defining cancers compared to people with HIV mono-infection, investigators from Spain report in the online edition of AIDS. Even after hepatocellular carcinoma was excluded, co-infection was associated with a 26% increase in the risk of non-AIDS-related cancers relative to HIV mono-infection.

But both groups had a higher risk of cancer compared to the general population.

Cancer prevention and screening should be a top priority in HIV care, suggest the authors, who believe their results underscore the importance of treating and eradicating HCV in people with co-infection.

As a result of antiretroviral therapy (ART), many people with HIV now have a near-normal life expectancy. However, rates of serious non-HIV-related illnesses are higher among people with HIV compared to individuals in the general population. Several studies have shown that even in the context of effective ART, people with HIV have an elevated risk of several malignancies not traditionally associated with HIV infection.

In high-income countries, approximately a third of people with HIV have HCV co-infection. This infection has been associated with an increase in liver cancer and also with certain other malignancies, including lymphoma.

Little is known about the impact of HCV co-infection on cancer risk for people with HIV.

Investigators in Coruña therefore designed a retrospective study involving adults with HIV who received care between 1993 and 2014. Incidence of cancer was compared between people with HIV and individuals in the general population. The investigators also compared cancer risk for people with HIV according to HCV co-infection status.

The study population consisted of 2318 people, 37% of whom had HCV co-infection. Only 17% of people with HIV and HCV co-infection had received HCV therapy (interferon based in all cases) and 48% of those who had received HCV therapy had a sustained virological response.

Study participants were followed for an average of twelve years and contributed 27,086 person-years of follow-up. A total of 185 people, 68 of whom had HCV co-infection, were diagnosed with a cancer. Overall cancer incidence was 696 cases per 100,000 person years.

Incidence of non-AIDS-defining cancers was higher among people with HIV and HCV co-infection compared to people with HIV mono-infection (415 vs 377 per 100,000 person-years).   

Cancer incidence overall was almost four-fold higher among people with HIV compared to the general population (SIR = 3.8; 95% CI, 3.3-4.4). Unsurprisingly, people with HIV had a massively increased incidence of AIDS-related cancers compared to individuals in the wider population (SIR = 27.2; 95% CI, 21.7-33.8). But HIV infection was also associated with a more than two-fold increase in the incidence of non-AIDS-related malignancies (SIR = 2.3; 95% CI, 1.9-2.80). This increased risk was present for people with HIV-mono-infection (SIR = 1.8; 95% CI, 1.3-2.3) and especially those with HCV co-infection (SIR = 3.4; 95% CI, 2.5-4.4).

As expected, incidence of AIDS-related cancers fell during follow-up but rates of non-AIDS-related cancers increased.

Older age was a risk factor for diagnosis with cancer. This was the case for both HIV-related and non-HIV-related malignancies.

People with HCV co-infection had a significantly increased risk of diagnosis with a non-AIDS-related cancer compared to people with mono-infection (SHR = 1.80; 95% CI, 1.15-2.81). Co-infection remained associated with increased risk of non-HIV-related malignancies after diagnosis with liver cancer was excluded (SHR = 1.26; 95% CI, 1.02-1.94).

“After adjusting for epidemiological factors and mortality without cancer, HIV/HCV-co-infected patients presented more NADC [non-AIDS-defining cancer] than HIV-mono-infected, even after excluding HCC [hepatocellular carcinoma],” conclude the authors. “Treatment of HCV infection and HIV replication control are fundamental strategies but the valuable role of cancer-screening programs and early treatment must be assessed.”