Pollutional haze as a potential cause of lung cancer

Lung cancer remains one of the most common cancers and accounts for the highest death toll of all cancer deaths among men and women (1,2). It is estimated that lung cancer accounts for more than one-quarter of all cancer in 2014 by American Cancer Society (ACS) (2). In spite of recent advances in screening and treatment, 5-year survival rate of lung cancer remains relatively low (3). Therefore, a better understanding the contribution of risk factors to lung cancer and prevention through lifestyle is needed for reducing the increasing burden of cancers worldwide (4). Results of several previous studies have already proved that smoking is a leading cause of lung cancer (5). However, it is notable that smoking cannot explain the relatively high rates of lung cancer which are observed among non-smokers and never-smokers. Therefore, some evidences suggested that other factors, such as environmental factors, family history of lung cancer and occupational exposures, also can contribute to lung tumorigenesis (6-8). More recently, the focus of scientists is shifting to one of the most serious yet ambiguous risk factor for lung cancer: air pollution, especially pollutional haze