Chronic obstructive pulmonary disease (COPD), which is a collection of lung diseases including emphysema and chronic bronchitis, is most often caused by smoking. Though smoking causes 85 – 90 % of the lung cancer cases, there are 10-15 % cases where people who never smoked get lung cancer. In the U.S. alone, this represents 16,000 to 24,000 cases a year. Non smokers develop lung cancer for reasons, such as genetic susceptibility, exposure to certain carcinogens, such as asbestos, radon, some solvents, and passive smoking, which is inhaling others’ cigarette smoke.
The study by researchers at the University of Texas, published in the journal Cancer Prevention Research, has found that African Americans who had a history of COPD were over six times as likely as those without the disease to develop lung cancer. This puts them on par in risk to that linked to smoking, and is twice as high as the risk linked to COPD in whites, said the researchers.
Lead researcher Dr. Carol Etzel, of the UT M.D. Anderson Cancer Center, said, "The one size fits all risk prediction clearly does not work." She was referring to previous studies which focused on white adults to predict an individual’s risk for lung cancer. However, the researchers feel that in all racial groups, various risk factors for lung cancer do not necessarily each carry the same weight.
Etzel and her colleagues studied 491 African Americans with lung cancer and 497 African Americans, who were matched to the patients for age and sex, but were free of cancer. In black adults similar to what has been seen in whites in previous studies, smoking, the major risk factor for lung cancer, was as strongly linked to the disease. Current smokers had a six times higher chance to develop lung cancer as non-smokers, while former smokers faced a more than three-fold increase in their risk.
In this study, the model they developed takes into consideration a person's history of smoking, COPD, hay fever -- which is linked to a lower lung cancer risk – as well as exposures to asbestos or wood dust, which raise the risk of the disease. The researchers found this to be a more accurate model in predicting black adults' lung cancer risk compared with a similar model that was previously developed from data on white patients.
"What we hope is that a doctor can use these models to encourage their patients to take steps to prevent lung cancer," she said. "Even if they are never smokers, they can be at risk."
In another study a group of researches led by Dr. Michael J. Thun, conducted a large-scale composite study. They used data from 13 other studies from North America, Europe, and Asia spanning 40 years and over 2 million people. They found that the death rate from lung cancer among non-smokers in general has been stable, with no marked increase detected. Non-smokers appear to have "different molecular profiles of, lung tumors and respond better to targeted therapies" than tumors in smokers' lungs.
Some other factors they found were that although men and women were equally likely to develop the disease at age 40 +, men were more likely to die of the disease regardless of age or racial group.
African Americans are more likely to die from the disease than are those of European descent as are Asians living in Korea and Japan, but not in the U.S., more likely to die of the disease than those of European descent. - The disease was not rising among non smoking women in the U.S. while it is more common in East Asian women than in other women.
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