Smoking appears to contribute more to the burden of non-AIDS-defining cancers diagnosed in people living with HIV in the US out of all potential modifiable risk factors - including hepatitis B or C, low CD4 cell count, an AIDS diagnosis or have an unfiltered viral load - according to a study reported last week in the Conference on Retroviruses and Opportunistic Infections (CROI 2015) in Seattle, USA.The study, presented by Keri Althoff of the Johns Hopkins Bloomberg School of Public Health, found that the Attributable Fraction of Population (PAF) - or the proportion of non-AIDS-defining cancer that can be prevented by people with HIV if they had the same level of smoking as the reference population - was 37% for all non-AIDS-defining cancers and 29% if lung cancer was excluded.
Cancer among people living with HIV
As noted by other presenters at the conference, the risk of AIDS-defining cancers is very high in people living with HIV, although these cancers have become less common since the introduction of antiretroviral therapy (ART). However, the risk of some other types of cancer is also high, and may be increasing among people with HIV - in particularly now that they reach older ages with effective HIV treatment.A number of factors contribute to this increased burden of non-AIDS-defining cancers, including increased frequency of smoking, recreational drugs or alcohol use, and higher rate of co-infections with other specific viruses associated with cancers such as hepatitis B virus (HBV) and hepatitis C virus (HCV), which can cause liver cancer, and human papillomavirus (HPV), which can cause anal, cervical, genital warts and oral cancer. In addition, HIV infection - whether chronic inflammation associated with HIV in the course of replication, or related to HIV immunosuppression - may also play a significant role in the development of non-AIDS-related cancer.
For example, a presentation by Keith Icahn Siegel of Medicine Mount Sinai School specifically examined the association between lung cancer related immune suppression in HIV cohort study (VOCs) with more than two years in a cohort of 26.065 Veterans living with HIV veterans with a control group in a group "natural aging".
This study demonstrated that having a mean CD4 cell count (over the period of 24 months) below 200 cells / mm3 was associated with a greater 70 risk of lung cancer, and having a CD4 cell count between 200 and 500 cells / mm3 was associated with a% 30 increased risk compared to people living with HIV and who had CDXUMUMX cell count above 4 cells / mm500. Similarly, having a CD3 / CD4 cell ratio below 8 was associated with an increase of 0,4% in the risk of lung cancer compared to higher rates. The immune system, however, does not appear to be associated with a higher rate of lung cancer / associated mortality, although it was associated with a larger overall than all other causes of mortality.
Although Siegel argued that this remains unproven, early and more efficient ART can reduce the risk of lung cancer and possibly other non-AIDS-defining cancers in people living with HIV / AIDS. However, a better understanding of how much cancer is due to various risk factors can help identify interventions that could prevent more cases.
Cancers unrelated to AIDS NA-ACCORD
This was the goal of the Althoff study, which analyzed the incidence of non-AIDS-defining cancer among 16 participants from the cohorts of the North American AIDS Cohort Collaboration for Research and Design (NA-ACCORD) from the 1 and January 2000 days 31 December 2009. The study included nearly 39.000 adults, about 600 of whom received new non-AIDS-defining cancers. Lung cancer was the most common non-AIDS-defining cancer diagnosed in this cohort.
Again, the aim of the study was to determine how much non-AIDS-defining cancer could be attributed to smoking compared to other HIV + patients related to risk factors. There are two key elements to be considered in calculating PAF: the prevalence of the risk factor - and the prevalence of smoking was quite high among AN-ACORDO participants - and the risk related to this factor.
Althoff concluded that in order to reduce the incidence of non-AIDS-defining cancers in adults living with HIV, effective interventions to reduce tobacco use are needed along with a continued focus on HIV treatment.
Overall, smoking had a much greater impact compared to the other risk factors that were considered. In fact, having a low CD4 cell count was a distant second in this analysis.
In other words, ONCE 37% of non-AIDS-defining cancers "could be avoided among individuals living with HIV if we were able to move them from the" never quit "category to" never smoking " , said Althoff, using ART to preserve immune function, maintain viral suppression, and halt progression to AIDS could prevent up to 8% of non-AIDS-defining cancers.
"We really need to start targeting individuals at risk for HIV and intervene for anti-smoking programs for young adults," she said.
She noted that a limitation of the study was that there was no available data on alcohol use, body mass index and HPV infection, so it is not possible to calculate the contribution of risk factors for cancer burden not AIDS-related.
In addition, data as follows: NA-ACCORD does not characterize the history of smoking - whether the participants were current smokers, the number of pack-years, whether or when they had to leave the study - so the study does not make it possible to determine the number of cancers that could have been prevented by cessation of smoking. In addition, while other studies are now collecting more stories of smokers, Althoff pointed out that very large cohorts may be needed to distinguish the effects of smoking cessation, especially among people who were previously heavy smokers.
Still, it can be said with certainty as Eric Engels of the National Cancer Institute said at the end of the eleventh session of the thematic discussion on cancer, "we have to do better to get people living with HIV live longer by quit smoking. "
Althoff KN et al. Smoking outweighs HIV-related risk factors for non-AIDS-defining cancers. 2015 Conference on Retroviruses and Opportunistic Infections (CROI), Seattle, abstract 726, 2015.
K Sigel et al. CD4 Measures the predictors of lung cancer risk and prognosis. 2015 Conference on Retroviruses and Opportunistic Infections (CROI), Seattle, abstract 728, 2015.Watch the Webcast of this presentation
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