[Association of tobacco and alcohol in cancer].

Heavy drinking and heavy smoking are often associated; the effects of either alcohol and tobacco on human cancer can not be easily disentangled. Appropriate adjustments need to be made to pinpoint the role of either factor. Both smoking and drinking play a role in cancer of the buccal cavity, pharynx and oesophagus; they seem to multiply their effects. Cancer of the larynx is also related to both alcohol and tobacco, but the role of alcohol appears only when exposure to tobacco is also present. While tobacco smoke is known to contain carcinogens, the mechanisms by which alcohol provoke cancer remain obscure; it may act by facilitating the penetration of carcinogens in the mucosa-carcinogens might be present in some alcoholic beverages; a direct action of ethanol can not be excluded. Epidemiological evidence is clear enough, however, to predict a substantial drop of incidence of buccal, pharyngeal, oesophageal and laryngeal cancers if alcohol and tobacco consumption could be reduced.