Smoking appears to contribute more to the burden of not defining cancers of AIDS diagnosed in people living with HIV in the United States, out of all the potential modifiable risk factors - including hepatitis B or C, low CD4 cell count, an AIDS diagnosis or have a viral load unfiltered - according to a study reported last week inConference 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 Population Attributable Fraction (PAF - acronym in English) - or not defining proportion of cancer that AIDS can be avoided by people with HIV if they They had the same level of smoke as the reference population - was 37% for all non defining cancers and AIDS 29% to lung cancer were excluded.
Cancer among people living with HIV
As noted by other presenters during 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 cancers is also high, and may be increasing among people with HIV - inparticularly now that they reach older ageswith the effective treatment of HIV.
A number of factors contributing to this increase in not defining cancer burden of AIDS, including increased frequency of smoking, recreational drugs or alcohol and higher rate of co-infection with other viruses associated with specific cancers, such as virus Hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, which can cause liver cancer and human papillomavirus (HPV), which can cause the anal warts, cervical, oral and genital cancer. In addition, HIV infection - the chronic inflammation associated with HIV replication stroke, or HIV-related immunosuppression - may also play a significant role in the development of AIDS-related non-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 CD4 having an average cell count (during the period of 24 months) below 200 cells / mm3 was associated with a 70% increased risk of lung cancer, and having a cell count between CD4 200 and 500 cells / mm3 was associated with a 30% increased risk compared with people living with HIV and had CD4 cell count above 500 cells / mm3. Likewise, having a CD4 / cell ratio CD8 below 0,4 it was associated with an increase of 70% in lung cancer risk compared with higher rates. The immune system, however, does not appear to be associated with increased lung cancer rate / mortality associated even though it was associated with an overall higher than all other causes of mortality.
Although Siegel said that this remains unproven, it is expected that HAART applied early and more efficient are likely to reduce the risk of lung cancer and possibly other non-defining cancers of AIDS in people living with HIV / AIDS. However, a better understanding of how cancer is due to several risk factors can help identify interventions that could prevent more cases.
Cancers unrelated to AIDS NA-ACCORD
That was the aim of the Althoff study, which analyzed the incidence of non-AIDS-defining cancer among 16 participants of the North American AIDS Cohort Collaboration cohorts of research and Design (NA-ACCORD) from the day January 1 2000 and December 31 2009. The study included almost 39.000 adults, some of whom received 600 new non-defining cancers of AIDS. Lung cancer was the most common AIDS defining not according to the cancer diagnoses in this cohort.
Again, the purpose of the study was to determine how much not defining cancer AIDS can be attributed to smoking compared to other HIV + patients related risk factors. There are two key elements to consider in calculating PAF: the prevalence of the risk factor - and the prevalence of smoking was very high among the AN-AGREEMENT participants - and the risk related to this factor.
Overall, smoking had a far greater impact compared to 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 prevented among people living with HIV if we could move them from the category" never quit "for the" never smoke '" , Althoff said, using ART to preserve immune function, maintain viral suppression, and halt progression to AIDS could prevent up to 8% of non-defining cancers of AIDS.
Althoff concluded that in order to reduce the incidence of the non-AIDS defining cancer in adults living with HIV, effective interventions to reduce tobacco consumption are required, along with a continued focus in the treatment of HIV.
"We really need to start targeting individuals at risk for HIV and intervene to preventive programs against smoking 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, the data as follows: NA-ACCORD not characterize the history of smoking - if the participants were current smokers, the number of pack-years, if or when they had to leave the study - so the study not possible to determine the number of cancers that could have been prevented by smoking cessation. Also, while other studies are now collecting more smokers stories, Althoff said that very large cohort may be necessary to distinguish the effects of smoking cessation, especially among people who previously were 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.
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