Lung cancer incidence rises to 20% among non-smoking women

The incidence of lung cancer among non-smokers reach 8% in males and nearly 20% among women, according to data from a study published in the "Journal of Clinical Oncology."

Lung cancer remains to this day the most deadly cancer. If tobacco is the main cause of this disease, however, it is more common in non-smokers for which data are limited.

Heather Wakelee, School of Medicine, Stanford University, and Ellen Chang, an epidemiologist at the Cancer Center of Northern California, have reviewed the scientific literature and current data on incidence and mortality from lung cancer among non-smokers from several cohort studies.

On more than one million people aged 40 to 79 years, who had never smoked, the researchers observed an incidence of lung cancer from 14.4 to 20.8 cases per 100,000 women-years and 4 8 to 13.7 cases per 100,000 man-years. This rate is 10 to 30 times higher in smokers, they said.

Reported to the U.S. population, these figures correspond to a ratio of about 8% of cases of lung cancer among non-smokers men and nearly 20% of cases in non-smoking women.

It is difficult to determine the factors responsible for lung cancer in non-smokers, however, it appears highly likely that passive smoking plays an important role, said Ellen Chang. It could also explain the difference in incidence between men and women, they are more often the victims of passive smoking than men, more likely to smoke.

"We know that passive smoking increases the risk of lung cancer, so it is likely that much of cases that we have observed is due to this," says the researcher.

Identify other risk factors for lung cancer in non-smokers is needed, particularly to help doctors understand how this cancer develops at the molecular level in order to develop new treatments, she added.