Fifty years of tobacco carcinogenesis research: from mechanisms to early detection and prevention of lung cancer.

The recognition of the link between cigarette smoking and lung cancer in the 1964 Surgeon General's Report initiated definitive and comprehensive research on the identification of carcinogens in tobacco products and the relevant mechanisms of carcinogenesis. The resultant comprehensive data clearly illustrate established pathways of cancer induction involving carcinogen exposure, metabolic activation, DNA adduct formation, and consequent mutation of critical genes along with the exacerbating influences of inflammation, cocarcinogenesis, and tumor promotion. This mechanistic understanding has provided a framework for the regulation of tobacco products and for the development of relevant tobacco carcinogen and toxicant biomarkers that can be applied in cancer prevention. Simultaneously, the recognition of the link between smoking and lung cancer paved the way for two additional critical approaches to cancer prevention that are discussed here: detection of lung cancer at an early, curable stage, and chemoprevention of lung cancer. Recent successes in more precisely identifying at-risk populations and in decreasing lung cancer mortality with helical computed tomography screening are notable, and progress in chemoprevention continues, although challenges with respect to bringing these approaches to the general population exist. Collectively, research performed since the 1964 Report demonstrates unequivocally that the majority of deaths from lung cancer are preventable.