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CROI 2016: Early Antiretroviral Therapy Reduces the Risk of Infection-Related Cancers

People who started antiretroviral therapy at a CD4 cell count above 500 had a significantly lower risk of developing a cancer with an infectious cause when compared to people who started treatment at a CD4 count of 350 or below, an analysis of the START study presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2016) in Boston has shown.

[Produced in collaboration with Aidsmap.com]

The primary analysis of the START studyshowed that early treatment reduced the risk of cancer by 64%, but did not differentiate between cancers of infectious and non-infectious causes. The analysis presented at CROI showed that early treatment reduced the risk of infection-related cancer by approximately 75% and halved the risk of non-infection-related cancers.

Cancers with infectious causes include those related to human papilloma virus or HPV (cervical cancer, anal cancer, and cancers of the head and throat), Kaposi sarcoma (HHV-8), and Hodgkin and non-Hodgkin lymphoma (Epstein-Barr virus). The viruses that contribute to the development of these cancers are more prevalent in many populations of people living with HIV, and so the prevention of these cancers is a particular priority in this group.

The START study randomized HIV-positive participants with CD4 cell counts above 500 cells/mm³ to start treatment immediately or defer treatment until their CD4 cell counts fell to 350 or below. The study found that early treatment reduced the risk of serious AIDS-related events, serious non-AIDS events, and death by 57%, and the risk of developing any cancer by 64%. When the findings were presented in 2015, investigators said that they found no difference in the impact of early treatment on cancers of infectious or non-infectious cause, but the analysis presented today has revisited the question in more detail.

There were 14 people in the immediate-treatment arm who developed cancer (6 infection-related and 8 infection-unrelated) compared to 39 people in the deferred-treatment arm, a reduction in risk of 74% for infection-related cancers (hazard ratio [HR] 0.26; 95% CI 0.11-0.64) and 51% for non-infection-related cancers (HR 0.49; 95% CI 0.21-1.15).

Overall, 29 cancers with an infectious cause occurred, 6 in the immediate arm and 23 in the deferred arm. These were predominantly Kaposi sarcoma (11 in the deferred arm and 1 in the immediate arm) and non-Hodgkin lymphoma (9 and 1, respectively). There was 1 case of Hodgkin lymphoma in each study arm, 1 case of anal cancer, and 1 case of cervical cancer in the immediate arm, and 2 cases of anal cancer in the deferred arm.

Overall, 24 cancers with a non-infectious cause occurred, 8 in the immediate arm and 16 in the deferred arm. Prostate and lung cancer occurred more frequently, and a wider range of cancers occurred in the deferred arm, but there was no substantial difference in the incidence of any particular cancer between the 2 study arms.

Whereas the annual cancer rate remained stable among people in the immediate group, the annual incidence of both infectious and non-infectious cancers increased over time in the deferred group.

Independent predictors of infection-related cancer were:

• Older age (1.42; 0.99-2.02 per 10 years);
• Higher body mass index (1.08; 1.01-1.16 per kg/m2);
• Low income region (0.32; 0.14-0.74 for high vs low income);
• Higher HIV RNA (2.32; 1.35-3.98 per 1 log higher).

Older age, however, was the only independent predictor of non-infection-related cancer (2.58; 1.75-3.81 per 10 years).

2/26/16

Reference

AH Borges, J Neuhaus, A Babiker, et al. Borges AH et al. Immediate ART Initiation Reduces Risk of Infection-Related Cancer in HIV. Conference on Retroviruses and Opportunistic Infections. Boston, February 22-25, 2016. Abstract 160.