Smoking and Oral Cancer

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Abstract

In the previous paper you have heard discussed the use of certain chemical compounds which, when applied to tissues, produce malignant neoplasms. Because of their cancerinducing properties, these compounds have been classified as "carcinogens" and, as such, are used principally as a means of producing tumors for experimental purposes. The obvious implication would be that these materials are research tools in the broad study of neoplastic disease and, therefore, are confined to laboratory use. While the substance of this paper also deals with laboratory procedures related to experimental oral neoplasia, its central theme will be the evaluation of still another entity that for many years has been suspected as an important link in the chain of factors influencing neoplastic transformation in oral and other tissues. Moreover, this substance is in widespread use by humans around the world. Although the tobacco habit has been popular among civilized populations since Elizabethan times, it has been only recently that its most widespread form of usecigarette smoking-has come under close scrutiny by cancer investigators. Initial interest in the relationship between smoking and cancer was prompted by the rather alarming increase in mortality from carcinoma of the lung in the last 30-35 years. The epidemiologic studies of Doll and Hill' in England and of Wynder and Graham2 and Hammond and Horn3-5 in the United States have strongly implicated the rise of cigarette consumption in the increased incidence of lung cancer. Other workers, however, while not ruling out tobacco as an etiologic agent in lung cancer, have proposed other factors on both epidemiologic and experimental grounds.6 7 With reference to an association of tobacco and oral carcinoma, Wynder, Bross, and Feldman8 have proposed a definite correlation between oral cancer and cigarette smoking, while Lilienfeld9 has stated that the relationship between oral cancer and the tobacco habit is a probable one. In this regard, it may be of some interest to examine mortality rates between 1930 and 1960 (Fig. 1) from oral and lung cancer in the United States.10 While the rise in lung-cancer rates since 1930 is represented by a 700 per cent increase (from 3.2 to 22.1 per 100,000), the oral-cancer rate is slightly down, beginning at 3.8 per 100,000 in 1930, peaking at 4.1 in 1944, and decreasing to 3.4 per 100,000 in 1960. When tobacco-consumption figures" are compared with these mortality rates for the same period, the association between lung cancer and cigarette smoking is readily apparent (Fig. 2). The relationship between tobacco consumption and oral lesions, however, is closely related only to snuff, pipe, and cigar habits, all of which demonstrate a slight decline. It is not intended that any specific conclusions are to be inferred from