In addition to the birth-cohort effect caused by the risk factors, the high incidence in men may also be explained by a higher prevalence of the ALDH2*2 allele in Han Chinese individuals and a higher level of tobacco use and alcohol consumption [17,30]; additionally, the odds ratio of ESCC has been reported to be higher in people with the ALDH2*2 allele if they have higher levels of tobacco use or alcohol consumption [19]. This evidence concerns the gene ALDH2 and esophageal squamous cell carcinoma.