As stratified variables, we selected categorical variables (sex, history of smoking, hypertension, DM, heart disease, lung disease, preoperative anemia, preoperative chemotherapy, ASA, endotracheal tube type, continuous anesthesia, operation type, vasoactive drug use, blood transfusion, postoperative ICU admission, respiratory failure, lung infection, anastomotic leakage, and surgical site infection) and continuous variables (age, PLT, AST, ALT, Scr, operation time, and blood loss) that were transformed into categorical variables. This evidence concerns the gene GPT and anemia (phenotype).