- Researchers reviewed 23 years of healthcare information from more than 19,000 people with HIV in Ontario
- Despite decreases in AIDS-related cancers, people with HIV had a 20% greater risk of cancer
- The researchers underscored the need for cancer screening and prevention strategies
When initiated and used as directed, after a few months, HIV treatment (ART) usually reduces the level of HIV in the blood to the point whereby it cannot be detected with routine laboratory tests. Continued use of ART helps keep HIV levels suppressed. As a result of this suppression of HIV, the immune system can begin to make repairs. Subsequently, the risk of AIDS-related infections becomes very rare. The effect of ART is so profound that researchers project that many ART users will have near-normal life expectancy.
However, ART cannot resolve all health issues related to chronic HIV infection. For instance, multiple studies have found that while ART can significantly reduce the level of excess immune activation and inflammation in the blood, it cannot restore them to normal levels. Some research suggests that persistent immune activation and inflammation can contribute to subtle defects in immunity.
As people with HIV live longer, thanks to ART, their immune systems gradually weaken as they age, just like everyone else’s. Also, according to some scientists, the combination of persistent excess immune activation and inflammation may increase the risk for cancer in people with HIV.
Cancers and HIV
Since the early 1980s, researchers noted that people with HIV were at heightened risk for some cancers, including the following:
- Kaposi’s sarcoma (KS) – caused by a virus called human herpes virus-8 (HHV-8)
- non-Hodgkin’s lymphoma – in some cases this has been linked to infection with Epstein-Barr Virus (EBV)
- invasive cervical cancer – caused by some strains of human papillomavirus (HPV)
Subsequent research has found that some people with HIV are co-infected with hepatitis B virus (HBV) and hepatitis C virus (HCV), which both increase the risk for developing liver cancer.
Some people with HIV also smoke and drink alcohol, which can also increase the risk for certain cancers.
Taken together, a number of factors such as viral co-infections, certain activities and immune suppression caused by HIV all can play a role in increasing the risk for some cancers in this population.
The Ontario study
A team of researchers in Ontario reviewed health-related information collected from 19,403 adults with HIV between January 1997 and November 2020. The researchers focused on cancer-related issues.
Over the course of the study, cases of AIDS-related cancer fell significantly. However, the level of cancers unrelated to AIDS remained stable. Initially, there were proportionally fewer cancer diagnoses in women with HIV than in men. However, in the latter years of the study, rates of cancer had reached similar levels in women and men.
Study details
For the purposes of their study, the researchers grouped cancers as follows:
AIDS-related cancers
- Kaposi’s sarcoma
- non-Hodgkin’s lymphoma
- cervical cancer
Non-AIDS-related cancers caused by viral infections
- HPV-related cancers of the anus, penis, throat, tongue, vagina and vulva
- H. pylori-related cancer of the stomach (H. pylori is a bacterium that can cause persistent stomach ulcers)
- liver cancer caused by HBV or HCV
- Hodgkin’s lymphoma and cancer of the nasal passages/throat (these can be caused by EBV)
Cancers unrelated to infections
- such as cancers of the breast, lungs, thyroid and many others
According to the researchers, participants (79% men, 21% women) were around 36 years old when they entered the study. Most were born in Canada and lived in urban areas.
Results
Over the course of the study, there were 1,275 new cases of cancer. Men were more likely to have AIDS-related cancers, while women tended to have cancers unrelated to infectious causes.
The five most commonly diagnosed cancers distributed by gender and in decreasing frequency were as follows:
Among men
- non-Hodgkin’s lymphoma
- Kaposi’s sarcoma
- prostate cancer
- lung cancer
- anal cancer
Among women
- breast cancer
- non-Hodgkin’s lymphoma
- lung cancer
- thyroid cancer
- uterine or ovarian cancer
Trends
Over the course of the study, cancer diagnoses fell among men. According to the researchers, this was due to a decrease in AIDS-related cancers.
Among women, cancer diagnoses increased over time, driven by cancers unrelated to infections.
Proportions of people with cancer
By the end of the study in November 2020, 17,181 participants were alive. Among these people, the proportions with a cancer diagnosis in specific periods were as follows:
- 0.8% had a cancer diagnosis in the past two years
- 1.8% had a cancer diagnosis in the past five years
- 3% had a cancer diagnosis in the past 10 years
Bear in mind
The researchers estimated that, overall, people with HIV had a risk for cancer that was 20% higher than that in people without HIV. However, they cautioned that other studies have found that people with HIV are not screened for cancer as frequently as people without HIV. As a result, it is possible that a proportion of people with HIV in the Ontario study had cancer but were undiagnosed (and subsequently died). Thus, the overall cancer risk for people with HIV is likely higher than what was estimated.
The researchers found that 3% of people with HIV in the study were cancer survivors.
Although the risk for AIDS-related cancers fell during the study, the researchers found that there was little change in rates of new cancers unrelated to AIDS.
As the researchers estimated that cancer is more likely among people with HIV, they encouraged doctors and nurses to “incorporate cancer prevention strategies as part of comprehensive HIV care.” The researchers stated that such strategies should include the following:
- discussing cancer risk with patients
- encouraging risk reduction such as smoking cessation
- encouraging certain interventions for cancer prevention, such as HPV vaccination, hepatitis C treatment and screening for HPV-related cancers and colorectal cancer
—Sean R. Hosein
Resources
North American study finds low CD4/CD8 ratio can help predict cancer risk in people with HIV – CATIE News
French researchers investigate second cancers in people with HIV who survived a first cancer – CATIE News
Second cancer risk after surviving Hodgkin's lymphoma in people with HIV – CATIE News
Changes in CD4+ cell count after cancer treatment linked to survival among HIV-positive people – CATIE News
Cancer – Government of Canada
Cancer – Government of Quebec
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