Ontario study explores cancer trends in people with HIV over 24 years

• Researchers analysed data from more than 40,000 people collected over 24 years
• Over the course of the study, people with HIV had a decreased risk for infection-related cancers
• The researchers proposed a range of interventions to reduce cancer risk in people with HIV

When taken as prescribed, HIV treatment (antiretroviral therapy, ART) reduces the amount of HIV in the blood. Three to six months after initiation and with continued use of ART, most people will have very low levels of HIV in their blood. These low levels are commonly called “undetectable.” Over time, continued suppression of HIV allows the immune system to largely repair itself. These repairs are sufficient to significantly reduce the risk for AIDS-related infections and cancer. The power of ART is so tremendous that researchers expect that many ART users will have near-normal life expectancy.

However, ART cannot resolve every issue related to chronic HIV infection. For instance, although ART helps to lower levels of immune activation and inflammation associated with HIV, it does not normalize them.

Among HIV-negative people, researchers think that excess inflammation likely contributes to an increased risk for the following conditions:

• cardiovascular disease
• cancer
• type 2 diabetes
• degenerative conditions affecting the brain
• fat accumulation in the liver
• thinning of bones
• loss of muscle tissue
• high cholesterol levels
• premature aging of the immune system

It is likely that chronic inflammation and immune activation in people with HIV contribute to the same issues.

The reasons for the excess chronic inflammation and immune activation in people with HIV may be related to one or more of the following issues:

• chronic low-level infection with cytomegalovirus (CMV), a member of the herpes virus family
• the passage of proteins from bacteria and fungi in the gut into the blood
• production of low levels of HIV proteins deep within the immune system

Exploring cancer in Ontario

A team of researchers at several universities in Ontario and the Ontario HIV Treatment Network (OHTN) have been analysing health-related information from 20,304 people with HIV. Researchers matched each of these people to data collected from a person without HIV (for a total of 20,304 people without HIV) of the same age, gender, place of residence and region of birth. Data were collected between January 1996 and November 2020.

Researchers divided the cancers that people developed into two main groups as follows:

• infection-related cancers (these are caused by different viruses and bacteria) – Kaposi’s sarcoma; lymphoma; cancers of the anus, genitals, head and neck; cancers affecting the liver, nose and stomach
• infection-unrelated cancers – cancers of the bladder, brain, breast, blood, colon/rectum, throat, lung, skin (melanoma), ovary, pancreas, prostate, testis, thyroid and uterus

Trends in cancers

Researchers found that, over time, the risk of infection-related cancers fell among people with HIV. They stated that among people with HIV, the risk of being diagnosed with an infection-related cancer fell from 19% at the beginning of the study to 10% in the latter years of the study. This decrease occurred because of an overall decline in infection-related cancers. We will return to this point later in this CATIE News bulletin.

Among people without HIV, there were no significant changes in rates of infection-related cancers.

Among people with HIV, the researchers did find an increased risk for cancers affecting the anus and liver.

Reasons for the changes

As mentioned earlier, there was an overall decline in infection-related cancers among people with HIV over the course of the study. The researchers attributed this to a decrease in AIDS-related cancers. They stated that this decrease in AIDS-related cancers was driven by more potent HIV treatments and earlier initiation of ART. Both of these factors have helped to strengthen the immune system against AIDS-related cancers (many of which are caused by viruses).

However, researchers did find an increased risk for cancers of the anus and liver among people with HIV. To reduce the risk for anal and liver cancer, the researchers proposed the following interventions:

• vaccination against human papillomavirus (HPV), some strains of which cause anal, genital and oral cancer. Unfortunately, such vaccination cannot help people already infected with HPV, so the researchers encouraged doctors to refer people with HIV to programs that screen them for HPV-related precancers and cancer.
• screening for and vaccination against hepatitis B virus (HBV). For people who are co-infected with HBV, there are treatments that can help control the virus.
• screening for, and when necessary, treatment of hepatitis C virus (HCV). Treatment can cure more than 95% of people with HCV.

The above interventions are for infection-related cancers. However, the researchers noted that excess fat in the liver (non-alcoholic fatty liver disease, NAFLD) can cause scarring of this vital organ. Scar tissue in the liver increases the risk for liver cancer. Factors linked to NAFLD include high blood pressure, type 2 diabetes and obesity. Interventions that target these issues may be useful in people with NAFLD.

—Sean R. Hosein

Resources

Cholesterol-lowering medicine found beneficial for people with HIV who are at low-to-moderate risk of cardiovascular disease – CATIE News

Large study confirms near-normal life expectancy for many people on HIV treatment – TreatmentUpdate 249

Dutch HIV study finds implementing anal cancer screening and treatment saves lives – TreatmentUpdate 248

Yale University study finds head and neck cancer linked to poor survival in people with HIV – TreatmentUpdate 248

French researchers investigate second cancers in people with HIV who survived a first cancer – CATIE News

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