CYP2C19 and esophageal squamous cell carcinoma: The CYP2C19*2 GA/AA genotype was significantly more prevalent in ESCC patients and individuals with at least one copy of the CYP2C19*2 A allele had a 3.19-fold increased risk (adjusted 95% confidence interval (CI): 2.21–4.61, P < 0.001) of ESCC compared with those without this allele.