Cigarette smoking and cancer of the lung. Is there really any etiologic relationship?

Many past, widely accepted medical beliefs have subsequently proved to be false. Although much has been written about possible causal relations of cigarette smoking to lung cancer, there is a good deal of evidence which does not fit this hypothesis. This report summarizes some of the reasons for believing that cigarette smoking is not an important etiologic agent in lung cancer. Recent studies have reemphasized the importance of genetic factors, and a large number of significant psychologic variables between smokers and nonsmokers. The mounting evidence incriminating air pollution must also be borne in mind.