Smokers with HIV 10x more likely to die from lung cancer

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LungCancerPeople living with HIV who adhere to antiretroviral therapy but smoke cigarettes are around 10 times more likely to die from lung cancer than from HIV itself, according to a study led by researchers at Massachusetts General Hospital (MGH). The report suggests that lung cancer prevention through smoking cessation should be a priority in the care of people living with HIV.

“Smoking and HIV are a particularly bad combination when it comes to lung cancer,” says Dr Krishna Reddy, of the MGH division of pulmonary and critical care medicine and the Medical Practice Centre (MPEC), who led the study. “Smoking rates are extraordinarily high among people with HIV, and both smoking and HIV increase the risk of lung cancer.”

People with HIV are living longer now thanks to antiviral medications, but smoking and HIV together put them at risk of developing lung cancer at a rate even higher than that among smokers not infected with HIV. “Lung cancer is now one of the leading killers of people with HIV, but most of these deaths can be prevented,” says Dr Rochelle Walensky – chief of the MGH division of infectious diseases, co-director of the MPEC and the Steve and Deborah Gorlin MGH research scholar – senior author of the study.

Using a computer simulation model of HIV, the researchers estimated the risk of lung cancer among people living with HIV in the US, based on whether they are current, former, or never smokers, how many cigarettes per day they smoke – or smoked for former smokers – and whether they consistently take antiviral medications. They also accounted for the risks of other diseases, like heart disease, that are increased by smoking.

The researchers found that nearly 25% of people who adhere well to anti-HIV medications but continue to smoke will die from lung cancer. Among smokers who quit at age 40, only about 6% will die of lung cancer. The authors also found that people with HIV who take antiviral medicines but who also smoke are from 6 to 13 times more likely to die from lung cancer than from HIV/Aids, depending on the intensity of smoking and their sex.

Heavy smokers are at even higher risk for lung cancer, with risks of lung cancer death approaching 30%. When the researchers focused on people who do not perfectly follow recommended HIV treatment – and who are thus at greater risk of dying from HIV/AIDS – lung cancer was still estimated to kill more than 15% of smokers.

Dr Travis Baggett, of the MGH division of general internal medicine and the Tobacco Research and Treatment Centre, co-author of the study, says: “Quitting smoking is one of the most important things that people with HIV can do to improve their health and live longer. Quitting will not only reduce their risk of lung cancer but also decrease their risk of many other diseases, such as heart attack, stroke, and emphysema.”

More than 40% of people living with HIV in the US smoke, compared with 15% of the general adult population. Given how common smoking is, the researchers also projected the total number of expected deaths from lung cancer among people currently receiving HIV care in the US, taking into account current smoking rates and the imperfect adherence to antiviral therapy that is frequently seen. They found that nearly 60,000 will die from lung cancer – about 10% of all people who are receiving HIV care in the US, including both smokers and nonsmokers.

Reddy says, “These data tell us that now is the time for action: smoking cessation programs should be integrated into HIV care, just like antiviral therapy.” Reddy is an instructor in medicine, Baggett is an assistant professor of medicine and Walensky is a professor of medicine at Harvard Medical School.

Abstract
Importance: Lung cancer has become a leading cause of death among people living with human immunodeficiency virus (HIV) (PLWH). Over 40% of PLWH in the United States smoke cigarettes; HIV independently increases the risk of lung cancer.
Objective: To project cumulative lung cancer mortality by smoking exposure among PLWH in care.
Design: Using a validated microsimulation model of HIV, we applied standard demographic data and recent HIV/AIDS epidemiology statistics with specific details on smoking exposure, combining smoking status (current, former, or never) and intensity (heavy, moderate, or light). We stratified reported mortality rates attributable to lung cancer and other non–AIDS-related causes by smoking exposure and accounted for an HIV-conferred independent risk of lung cancer. Lung cancer mortality risk ratios (vs never smokers) for male and female current moderate smokers were 23.6 and 24.2, respectively, and for those who quit smoking at age 40 years were 4.3 and 4.5. In sensitivity analyses, we accounted for nonadherence to antiretroviral therapy (ART) and for a range of HIV-conferred risks of death from lung cancer and from other non–AIDS-related diseases (eg, cardiovascular disease).
Main Outcomes and Measures: Cumulative lung cancer mortality by age 80 years (stratified by sex, age at entry to HIV care, and smoking exposure); total expected lung cancer deaths, accounting for nonadherence to ART.
Results: Among 40-year-old men with HIV, estimated cumulative lung cancer mortality for heavy, moderate, and light smokers who continued to smoke was 28.9%, 23.0%, and 18.8%, respectively; for those who quit smoking at age 40 years, it was 7.9%, 6.1%, and 4.3%; and for never smokers, it was 1.6%. Among women, the corresponding mortality for current smokers was 27.8%, 20.9%, and 16.6%; for former smokers, it was 7.5%, 5.2%, and 3.7%; and for never smokers, it was 1.2%. ART-adherent individuals who continued to smoke were 6 to 13 times more likely to die from lung cancer than from traditional AIDS-related causes, depending on sex and smoking intensity. Due to greater AIDS-related mortality risks, individuals with incomplete ART adherence had higher overall mortality but lower lung cancer mortality. Applying model projections to the approximately 644 200 PLWH aged 20 to 64 in care in the United States, 59 900 (9.3%) are expected to die from lung cancer if smoking habits do not change.
Conclusions and Relevance: Those PLWH who adhere to ART but smoke are substantially more likely to die from lung cancer than from AIDS-related causes.

Authors
Krishna P Reddy; Chung Yin Kong; Emily P Hyle; Travis P Baggett; Mingshu Huang; Robert A Parker; A David Paltiel; Elena Losina; Milton C Weinstein; Kenneth A Freedberg; Rochelle P Walensky

Massachusetts General material
JAMA abstract
JAMA Editor’s note


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