Researchers in a study found that while 85 to 90% of lung cancer cases affect smokers, the remaining 10-15 % of people who contract the disease despite have never having smoked in their life. Further research showed that men seem more likely to die from the disease than women though the reasons are not clear.

In the U.S. alone 16,000 to 24,000 never-smokers a year die from the disease and according to the American Cancer Society nearly 1.5 million people die from lung cancer every year around the world due to tobacco smoking. Genetic susceptibility, exposure to certain carcinogens such as asbestos, radon, some solvents, as well as passive smoking or  inhaling others’ cigarette smoke are some of the likely causes feel experts.

A group of researches led by Dr. Michael J. Thun, from the American Cancer Society conducted the research using data from 13 other studies from North America, Europe, and Asia over a period of 40 years and covering over 2 million people in an attempt to better understand how lung cancer affects men and women in different cultures and from different time periods.

The researchers found that though men and women over the age of 40 had similar rates of lung cancer, men regardless of age or racial group were more likely to die of the disease as compared to women.  African Americans and Asians living in Korea and Japan, but not in the U.S., are more likely to die from the disease than are those of European descent.

Though the disease doesn't seem to be rising among women in the U.S. it was more common in East Asian women than in other women.

The findings appear in September's issue of PLoS Medicine and published with the study’s result the researchers in background information mentioned that tumors in the lungs of people who are not smokers have "different molecular profiles and respond better to targeted therapies" than do tumors in smokers' lungs.

As the findings of this study contradict with earlier ones researchers feel further study is needed to conclusively prove anything.