INS and chronic obstructive pulmonary disease: The preoperative factors included patient’s age, gender, BMI, smoking and alcohol intake, malnutrition status, ASA index, cardiovascular disease (aortic calcification, celiac trunk calcification, peripheral vascular disease, cardiac arrhythmia, and hypertension), obstructive lung diseases test scores (forced vital capacity ratio [FEV1%], transfer factor for carbon monoxide [TLco]), surgical history (abdominal surgery), drug usage (insulin and hypertension drugs), and cancer staging (TNM classification of malignant tumors).