Risk factors for colorectal cancer are: family history, inflammatory bowel disease, smoking, excessive alcohol consumption, high consumption of red meat or cured meat, obesity, and diabetes. Protective factors for colorectal cancer are: physical exercise, taking aspirin, colonoscopy and cutting out precancerous lesions, and some relatively weak protective factors such as food rich in fruits, vegetables, grains, dairy products, fish, and lipid-lowering drugs. Knowing the risk factors and protective factors, we know how to prevent colorectal cancer more effectively. Regular and regular follow-up is crucial for postoperative colorectal cancer patients by: 1. Medical history and physical examination every 3-6 months for 2 years, then every 6 months for a total of 5 years, and once a year after 5 years. 2. Monitoring of CEA and CA19-9 every 3-6 months for 2 years, then every 6 months for a total of 5 years, and annually after 5 years. 3, Abdominal/pelvic ultrasound and chest X-ray every 3-6 months for 2 years, then every 6 months for a total of 5 years, and annually after 5 years. 4.Abdominal/pelvic CT or MRI once a year. 5.Colonoscopy within 1 year after surgery, if there is any abnormality, review within 1 year; if no polyp is seen, review within 3 years; then once every 5 years, resection is recommended for any colorectal adenoma that appears in the follow-up examination. 6.PET-CT is not a routinely recommended examination item.