The relationship between carcinoembryonic antigen and bowel cancer is not absolute. Although carcinoembryonic antigen is elevated in some patients with bowel cancer, a significant proportion of patients do not have elevated carcinoembryonic antigen, so a normal carcinoembryonic antigen does not necessarily mean that you do not have bowel cancer. Carcinoembryonic antigen is a broad-spectrum tumor marker, which can be elevated in patients with gastric, pancreatic, bile duct, and colorectal cancers. However, its organ-specificity is relatively poor and its positivity rate is not ideal, so it has limited diagnostic value for bowel cancer, especially for early diagnosis. Carcinoembryonic antigen is mostly used to evaluate the prognosis of patients with bowel cancer and to monitor the recurrence of metastasis. If carcinoembryonic antigen decreases and then increases after surgery, the possibility of recurrence or metastasis should be suspected. Enteroscopy is the best examination method for bowel cancer, which not only can directly observe whether there is any lesion in the intestinal mucosa with naked eyes, but also can take biopsy for pathology examination for further diagnosis. Patients who are suspected of having intestinal cancer are recommended to go to the hospital as soon as possible to complete the colonoscopy.