Background. Esophageal melanosis is often observed in alcoholic Japanese men, in whom the prevalence of squamous cell dysplasia and carcinoma (SCC) in the upper aerodigestive tract are high. This study evaluated the associations of esophageal melanosis with these neoplasms, and the factors contributing to the development of esophageal melanosis in this population. Methods. Endoscopic screening was combined with esophageal iodine staining in 1535 alcoholic Japanese men (aged 40-79 years), of whom 1007 underwent aldehyde dehydrogenase-2 (ALDH2) genotyping. Results. Fifty patients (3.3%) were diagnosed with esophageal melanosis, which had a higher incidence in those with noncancerous distinct iodine-unstained lesions (DIULs; 16/268; 6.0%), esophageal SCC (9/66; 13.6%), and oropharyngolaryngeal SCC (4/19; 21.1%) than in cancer- and DIUL-free controls (24/1182; 2.0%). The presence of esophageal melanosis was associated with higher risks for noncancerous DIULs, esophageal SCC, and oropharyngolaryngeal SCC (odds ratios, 2.81, 6.54, and 14.77, respectively). Men with the inactive ALDH2*1/ 2*2 genotype had a higher risk for esophageal melanosis (2.66-fold), as well as for DIULs and SCCs. Conclusions. The presence of esophageal melanosis in alcoholic Japanese men could indicate a high risk for DIULs and SCCs in the upper aerodigestive tract. The high incidence of esophageal melanosis may be partially linked to high acetaldehyde exposure, a consequence of drinking alcohol in persons with inactive ALDH2.
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