The upper aerodigestive tract is a preferential site for multiple primary cancer. The purpose of this study was to determine the characteristics of patients presenting with at least two simultaneous cancers of the upper aerodigestive tract compared with patients with a single location. Men patients (2,738) with squamous cell carcinoma were enrolled in the study. Of these, 120 (4.4%) presented with at least 2 simultaneous cancers (cancers detected within a 6-month period). The group of patients with simultaneous cancers was compared with a group presenting with a single location. Two factors (the mean daily alcohol consumption and employment as a "blue-collar" worker at any time during the working life) seem to be related to the occurrence of simultaneous cancers.