May 24, 2012
Simply having HIV is an independent risk factor for lung cancer, according to a recent study from the U.S. Department of Veteran Affairs.
The researchers found that having HIV increased the risk of developing lung cancer by about 71%, after controlling for potential confounders, such as age, sex, race/ethnicity, smoking prevalence, previous bacterial pneumonia and chronic obstructive pulmonary disease.
The investigators compared and analyzed data from the Veterans Aging Cohort Study and the Veterans Affairs Central Cancer registry. They compiled data from 32,794 HIV-infected individuals and 75,750 HIV-uninfected individuals. There were 457 new cases of lung cancer in the HIV-infected group (an incidence rate of 1.4%), compared with 614 cases in the HIV-uninfected group (an incidence rate of 0.8%).
About 98% of the study participants were men, and half the study was black. The mean age was 46 years. The percentage of current smokers between the HIV-infected group (48%) and HIV-uninfected group (46%) was similar. The percentage of participants drinking alcohol was also similar: 16% in the HIV-infected group and 15% in the HIV-uninfected group. The HIV-positive group was more likely to have hepatitis C (35% vs. 15%).
It's important to note the other risk factors for lung cancer, which included older age, being a current or former smoker, having a history of chronic obstructive lung disease and a history of bacterial pneumonia.
Cancer stage at the time of diagnosis was similar for the HIV-positive and HIV-negative participants. "The increased incidence of lung cancer among the HIV infected patients does not appear to be explained by more vigilant surveillance," comment the investigators.
Although they found no significant association between lung cancer risk and current CD4 cell count or viral load, the researchers note that such associations have been found in other studies. They write: "For the purposes of understanding the relationship between immunodeficiency and lung cancer risk among HIV infected patients, we plan to conduct more sophisticated analyses with time-updated modeling of CD4 cell count."
The authors believe their findings may actually under-represent both the incidence and risk of lung cancer for patients with HIV. They therefore conclude: "Additional investigations are required to understand the mechanisms by which HIV infection may increase the risk for lung cancer."
Interestingly, these results come on the heels of a Swiss study in January that found cigarette smoking to be the most important risk factor of lung cancer in people living with HIV. That study also did not find having a low CD4 count or a history of AIDS-defining lung diseases associated with lung cancer.
Warren Tong is the research editor for TheBody.com and TheBodyPRO.com.
Follow Warren on Twitter: @WarrenAtTheBody .
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