Invited commentary: the etiology of lung cancer in men compared with women.

Lung cancer is the leading cause of cancer death among women in the United States and other Western nations. The predominant cause of lung cancer in women is active cigarette smoking. Secondhand exposure to tobacco smoke is another important cause. The hypothesis that women are more susceptible than men to smoking-induced lung cancer has not been supported by the preponderance of current data, as noted by De Matteis et al. (Am J Epidemiol. 2013;177(7):601-612) in the accompanying article. However, aspects of lung cancer in men and women continue to indicate potential male-female differences in the etiology of lung cancer, based on several observations: 1) among never smokers, women have higher lung cancer incidence rates than men; 2) there is evidence that estrogen may contribute to lung cancer risk and progression; and 3) there are different clinical characteristics of lung cancer in women compared with men, such as the higher percentage of adenocarcinomas in never smokers, the greater prevalence of epidermal growth factor receptor gene (EGFR) mutations in adenocarcinomas among never smokers, and better prognosis. Considered in total, observations such as these offer enticing clues that, even amid cigarette smoking and other commonalities in the etiology of lung cancer in men and women, distinct differences may remain to be delineated that could potentially be of scientific and clinical relevance.