Interaction of alcohol and tobacco as risk factors in cancer of the laryngeal region.

The aim of this study is to present risk assessments for the combined effect of alcohol and tobacco in cancer of the larynx. The case control study included all newly diagnosed laryngeal cancer patients under the age of 75 in Denmark during the years 1980-2. Four age and sex matched controls were selected using the municipal person registry in which the case was listed. Ninety six per cent of all cases and 78% of controls participated in the study, which is based on 326 cases and 1134 controls. Information on alcohol consumption and tobacco use was obtained by means of mailed questionnaires. For all laryngeal cancers as well as for the subgroups concerning cancer of the glottis and supraglottis alcohol consumption and tobacco use were found to be important risk factors. The effect of joint exposure was greater than the effect predicted from the sum of effects of each factor acting separately. Thus the combined effect follows a multiplicative rather than additive model.