Abstract:Objective To investigate the expression of apurin and apyrimidine endonuclease 1 (APE1) in colorectal cancer and its relationship with clinicopathological characteristics and prognosis. Methods Colorectal cancer tissues and their adjacent tissues of 100 colorectal cancer patients from October 2015 to September 2017 in Taizhou Hospital of Zhejiang Province were selected. Immunohistochemical staining was used to determine the expression of APE1 protein in colorectal cancer tissues and adjacent tissues. Results The high expression rate of APE1 in colorectal cancer tissues was higher than that in adjacent tissues (P < 0.05). APE1 expression was significantly different in different tumor sizes, tumor stages, lymph node metastasis and distant metastasis (P < 0.05). APE1 positive expression rate of patients with tumor diameter ≥ 5cm, tumor stage III-IV, lymph node metastasis, distant metastasis in colorectal cancer tissues were higher than patients with tumor diameter < 5cm, tumor stage Ⅰ-Ⅱ, no lymph node metastasis and no distant Transferer. There were no significant difference in the expression of APE1 in different ages, genders, tumor locations and degrees of differentiation (P > 0.05). The overall survival rate of the APE1 high expression group was lower than that of the APE1 low expression group (P < 0.05). The analysis of COX proportional hazard model showed: APE1 expression [Hl ^ R=1.198 (95% CI: 1.102, 1.276), P = 0.000], tumor stage [Hl ^ R=1.426 (95% CI: 1.358, 1.492), P = 0.000], lymph node metastasis [Hl ^ R=1.384 (95% CI: 1.306, 1.457), P = 0.000], distant metastasis [Hl ^ R=1.735 (95% CI: 1.164, 2.237), P = 2.237] were independent influencing factors for the overall survival of colorectal cancer. Conclusion APE1 expression is increased in colorectal cancer tissues. APE1 is closely related to tumor size, tumor stage, lymph node metastasis, distant metastasis and prognosis of colorectal cancer.