Another Blow for Asthma Sufferers
May 10, 2000 (Toronto) -- If you have asthma and smoke, you have another reason to stop. People with asthma who have never smoked have a higher risk of getting lung cancer than the general population, and those who also smoke have an even higher risk, according to a review of research presented here at a meeting of the American Thoracic Society.
This finding should not cause panic among asthma patients, though, lead researcher Alfredo A. Santillan, MD, tells WebMD. "Asthma is a risk factor for lung cancer. [H]owever, only a small fraction of asthmatics are prone to develop lung cancer because of asthma," says Santillan, noting that the increased risk, almost two times above the general population, is still relatively low. "Those who are current smokers probably are at higher risk and should avoid cigarette smoking."
Asthma patients who were former smokers were more than two times more likely to get the disease. Santillan is a research physician in the medical school at the Institute of Advanced Studies in Monterrey, Mexico.
Prior research has identified links between other types of noncancerous lung disease, such as emphysema and chronic bronchitis. Because the association between asthma and the risk of lung cancer has not been proven, Santillan and co-authors at Massachusetts General Hospital in Boston reviewed the studies completed up to this point to see if they could reach a conclusion.
And reach a conclusion they did, Santillan tells WebMD. He says that even when the analysis was limited to people who had never smoked, the data suggested a direct relation between asthma and lung cancer.
Investigators have yet to determine why asthma would make individuals more susceptible to lung cancer. The most likely explanation, Santillan says, may be the way that several facets of asthma interact with the environment. These include impaired lung function, chronic inflammation of the airways, and alterations in the immune system, which fights off disease. Therefore, they may be more vulnerable to cancer-causing agents, found in second-hand smoke, the by-products of heating and cooking, and air pollution, and substances such as asbestos and arsenic that could be encountered in certain jobs.
"[T]he most important [finding] derived from this study is that asthmatics should avoid smoking cigarettes," Santillan tells WebMD. "Despite the ? impairment observed in asthma, asthmatics still continue to smoke," at a rate of approximately 20% to 60%. Therefore, the risk of lung cancer among asthma patients is high because of asthma, because of smoking, and because of both factors combined, he says.