Similarly, ALDH2*2, alcohol drinking and smoking were also associated with high incidents of HNSCC in patients with ESCC; Katada et al. screened 71 esophageal cancer patients and found that 29.5% of the ESCC patients also had HNSCC [45] and 95% of these patients carried the ALDH2*2 allele, 90% were also smokers and 100% of these patients consumed alcohol [45]. This evidence concerns the gene ALDH2 and head and neck squamous cell carcinoma.