In another subgroup analysis by cancer types, we found that CYP2C19 PMs genotypes led to an increased incidence of esophagus cancer, gastric cancer, lung cancer and head neck cancer as well as hepatocellular carcinoma, but not for breast cancer, colorectal cancer, leukemia, prostate cancer, bladder cancer and biliary tract cancer. This evidence concerns the gene CYP2C19 and head and neck cancer.