(Ivanhoe Newswire) – About 15 percent of people with lung cancers have never smoked. A new study finds the cause could be linked to cells that cannot repair efficiently from environmental insults.

The research was conducted by investigators from M.D. Anderson Cancer Center. Researchers drew white blood cells from 219 lung cancer patients and 309 matched participants who had never smoked. They used the cells to conduct tests to see how they would react to all kinds of smoke including tobacco that is highly carcinogenic.

Study authors found nonsmokers with suboptimal DNA repair capacity (DRC) are almost twice as likely to develop lung cancer, compared with nonsmokers with normal DRC. Study participants with the lowest ability to repair their DNA had a more than a threefold increased risk, compared with individuals with efficient DRC. Investigators were not able to pinpoint the gene or genes that cause DRC, but they say the data suggests it could be heritable.
 

Researchers also found secondhand smoke exposure as another risk factor for non-smoking lung cancer. They say those with inefficient DRC had a risk of lung cancer that was almost fourfold. Study authors say many people think they are not at risk of lung cancer because they don’t smoke, but they caution anyone who has a non-smoking relative with lung cancer to avoid all carcinogens including tobacco smoke.

SOURCE: Cancer, Epidemiology, Biomarkers and Prevention, June 2008