Tobacco and alcohol consumption in relation to the development of multiple primary cancers.

The relationship between tobacco and alcohol consumption and the development of additional primary cancers of the upper alimentary tract is reviewed. The chance of developing a second primary is dependent principally on the intensity (i.e., quantity and duration) of the smoking and drinking habit prior to the onset of the first neoplasm. However, results conflict regarding the effect exerted by the continuation of these habits after the first diagnosis. While tobacco smoking is considered the primary risk factor associated with cancers in this area, its interaction with alcohol creates a powerful carcinogenic effect. It is agreed that multiple primaries are selective on a site-specific basis and that risk varies with anatomic location of the first primary.