1.Prevention and care (1) Appropriately reduce the fat and meat content of diet and increase fresh vegetables and fruits. (2) Colorectal adenomas should be periodically reviewed and promptly removed. (3) For chronic inflammatory diseases of colorectum, especially long-term chronic ulcerative colorectitis, we should be alert to the occurrence of cancer, and carry out regular rectal diagnosis, X-ray or fiberoptic colonoscopy. (4) For patients over 50 years old, fecal occult blood should be examined twice a year, which can help to detect colon cancer with inconspicuous symptoms earlier. 2. Postoperative follow-up (1) Follow-up every 3 months for 2 years after operation, especially the first follow-up should be conducted in March after operation. Each follow-up should include medical history and detailed physical examination, blood CEA and other tumor markers, immune function status, blood routine, liver function, fecal occult blood test, chest X-ray and ultrasound scanning of liver, peritoneal lymph nodes and pelvis. (2) Fiberoptic enteroscopy is required once a year to detect heterochronous polygenic neoplasm and anastomotic recurrence, with an additional barium enema in between. If fiberoptic enteroscopy and barium enema are not performed preoperatively for some reason, one of them should be examined 6 months after surgery. CT or MRI examination once a year, the first CT and enteroscopy should be reviewed within six months. (3) Follow-up 2 to 5 years after surgery can be extended to every 6 months. For patients more than 5 years after surgery, it can be once every 1 year, or combined with health checkup plus key items. (4) For patients receiving postoperative adjuvant chemotherapy, CEA and liver function can be increased to once every 1-2 years. Abnormalities found during follow-up should be examined in detail for early detection of recurrence and metastatic lesions. Blood counts should be checked routinely, at least once a week in patients with DPD enzyme deficiency or patients with significant myelosuppressive drugs.