HIV infection independently increases lung cancer risk by 70%, according to the largest study yet to examine the issue.
"After adjusting for smoking and traditional lung cancer risk factors, we do still find that there is some independent mechanism related to HIV that's increasing lung cancer risk in the HIV-infected population," Dr Keith Sigel of the Mount Sinai School of Medicine in New York City, the study's first author, said.
People with HIV are known to be at increased risk of lung cancer, Dr Sigel and his colleagues note in their study, published in Aids online. But it has not been clear, they add, whether this is because they are more likely to be smokers, or due to surveillance bias.
To investigate, the research team linked data from the Veterans Aging Cohort Study Virtual Cohort to the Veterans Affairs Central Registry.
No difference in diagnose
From a total of 37,294 people with HIV and 75,750 non-infected individuals, 1,071 developed lung cancer. Lung cancer rates per 100,000 person-years were 204 in the HIV cohort and 119 in the control group.
After the researchers adjusted for smoking, age, sex, race, chronic obstructive pulmonary disease, and previous pneumonia, the incidence rate ratio for HIV and lung cancer was still significant, at 1.7.
There was no difference in stage at diagnosis between HIV patients and controls, suggesting that surveillance bias was not a factor in the higher rate of lung cancer in the HIV group.
Lung cancer aggressive in HIV?
HIV infection itself could boost lung cancer risk by suppressing the immune system, and also by causing chronic inflammation, Dr Sigel noted.
"The impact of smoking raises risk 70%, so smoking is still the number-one area to target," he added. "It just highlights again that smoking cessation is such an important issue for patients with HIV. Also, I think this will lead to some interesting work into looking at the benefits of lung cancer screening in people with HIV."
It will be important to determine, he added, whether screening HIV-infected individuals for lung cancer has the same benefits as screening people without HIV, more benefit, or less benefit. Another key question that needs to be answered, he said, is whether lung cancer is more aggressive in people with HIV.
(Anne Harding, Reuters Health, March 2012)