ObjectiveTo investigate the incidence of perioperative anemia and the influencing factors of preoperative anemia in patients with colorectal cancer.MethodsThe clinicopathological data of 1 250 patients with colorectal cancer who underwent surgery in our hospital from January 1, 2019 to December 31, 2019 were analyzed retrospectively. According to the preoperative hemoglobin level, patients were divided into anemia group and non-anemia group. Univariate analysis and multivariate logistic regression analysis were used to explore the influencing factors of preoperative anemia in patients with colorectal cancer, and the effects of preoperative anemia on intraoperative blood transfusion, postoperative complications, and postoperative hospital stay were analyzed.ResultsThe incidence of preoperative anemia in patients with colorectal cancer was 40.6% (508/1 250), and the incidence of preoperative anemia in patients with right colon cancer, left colon cancer, and rectal cancer was 66.0% (192/291), 41.1% (139/338), and 28.5% (177/621), respectively. The incidence of postoperative anemia in patients with colorectal cancer was 69.4% (867/1 250), and the incidence of postoperative anemia in patients with right colon cancer, left colon cancer, and rectal cancer was 81.8% (238/291), 68.9% (233/338), and 63.8% (396/621), respectively. Multivariate logistic regression analysis showed that age >60 years old, nutritional risk screening 2002 ≥3, right colon cancer, T3–4 stage, and M1 stage were risk factors for preoperative anemia in patients with colorectal cancer (P<0.05). The rate of intraoperative blood transfusion and the incidence of postoperative complications in the preoperative anemia group of patients with colorectal cancer were higher than those in the non-anemia group (P<0.05). The postoperative hospital stay in the preoperative anemia group of patients with colon cancer was longer than that in the non-anemia group (P<0.05).ConclusionsThe incidence of perioperative anemia in patients with colorectal cancer is high. Advanced age, high nutritional risk, right colon cancer, T3–4 stage, and distant metastasis were the risk factors of preoperative anemia in patients with colorectal cancer. Preoperative anemia can increase the demand for intraoperative blood transfusion and the incidence of postoperative complications in patients with colorectal cancer, and prolong postoperative hospital stay of colon cancer patients.