Inclusion criteria and exclusion criteria
gastroenteric tumors, left colon cancer, colon cancer, radical right colon cancer
TRANSVERSE COLON CANCER, COLON CANCER, RECTAL CANCER, SIGMOID COLON CANCER
The inclusion criteria were adult patients ≥ 65 years old undergoing elective open radical resection of gastroenteric tumors (radical gastrectomy includes total gastrectomy, partial gastrectomy at the upper root, and partial gastrectomy at the lower root; radical resection of rectal cancer includes Dixon surgery, Miles surgery, Hartmann surgery; radical colon cancer operations include radical right colon cancer, radical left colon cancer, transverse colon cancer, and sigmoid colon cancer), body mass index (BMI) 15–30 kg m