Introduction
Tobacco-related deaths now exceed 5 000 000 each year worldwide. Lung cancer, one of the major to baccorelated diseases, is a leading cause of cancer death in the world, and its incidence is still increasing. Tobacco smoke-derived toxic compounds such as aromatic hydrocarbons have been proved to cause lung carcinogenesis 1,2 and the increasing mortality from lung cancer is closely associated with the consumption of tobacco.3 Despite campaigns to prevent people from smoking in an attempt to decrease lung cancer mortality,4 the population of smokers worldwide continues to increase.5,6 It remains unclear whether tobacco smoking affects the progression of lung cancer. Benzo(a)pyrene [B(a)P], one of the major carcinogens in cigarette smoke, can induce molecules that cause inflammation, and cellular proliferation and migration. Thus, it has been suggested that tobacco smoke-derived aromatic hydrocarbon compounds modulate cancer progression. In this review, we discuss the findings of recent investigations addressing this issue.