Some smokers may be more susceptible to DNA damage from tobacco smoke and thus more likely to develop lung cancer. The preliminary findings from a population study, reported in the 15 April issue of the journal Cancer, identify one of many long-sought genetic factors that may increase one's susceptibility to this disease. If the findings are borne out, they might eventually lead to a blood test for screening people susceptible to lung cancer.
Although 90% of all lung cancers are linked to tobacco smoke, only about 10% of smokers get cancer. To probe why some smokers are susceptible and others are not, Xifeng Wu and Margaret Spitz at the M. D. Anderson Cancer Center in Houston and their colleagues studied alterations in chromosome 9. Other groups had observed that in tumor cells from patients with lung cancer, this chromosome often is missing part of its DNA or has gained a piece of another chromosome--a problem attributed to DNA-damaging carcinogens in tobacco.
Wu and Spitz studied chromosomes of normal cells--in this case, white blood cells--drawn from 97 Mexican- and African Americans newly diagnosed with lung cancer. The researchers interviewed the participants about their lifestyles and family cancer history, as part of a study on lung cancer risk factors in minorities. Of the group, 43 had missing sections or other alterations in chromosome 9. People with the genetic damage were 8.5 times more likely to have relatives with lung cancer than were those with normal copies of chromosome 9. "It suggests there might be some form of genetic instability" in the chromosome that can be inherited, Spitz says.
The results suggest a potential "inherited genetic susceptibility" to tobacco smoke, says molecular biologist Dawn Willis of the American Cancer Society in Atlanta, one that may put some smokers at an increased risk for lung cancer. First, however, more rigorous studies are needed to confirm the hypothesis, cautions oncologist Michael Kelley of the National Cancer Institute in Bethesda, Maryland. The number of subjects was small and was restricted to minority populations; therefore, he says, the findings "may simply be due to chance."