On May 27, 1950, Washington University physician Evarts A. Graham, MD, and medical student Ernst Wynder published a landmark study that first linked smoking and lung cancer entitled: “Tobacco Smoking as a Possible Etiologic Factor in Bronchiogenic Carcinoma: A Study of Six Hundred and Eighty-Four [684] Proved Cases.”

Their study provoked the American Medical Association and British Medical Research Council to address the causation issue. The AMA responded by refusing to accept tobacco advertising in their journal; however, leadership rejected the link of tobacco to lung cancer as causal and considered it to be correlational only.

Smoking and lung cancer has a strong, pragmatic, multiple causal associations, meaning the incidence of smoking decreases when exposure to smoking decreases. Causation of chronic disease includes the identification of a host of environmental conditions and behaviors (vectors/vehicles) which may contain a causative agent for that disease to develop.