Colorectal cancer has the possibility of multiple occurrences at the same time or at different times, therefore, patients after colorectal cancer treatment are the high-risk group for recurrence of colorectal cancer. There is no effective method to avoid the occurrence of early tumors, however, through regular follow-up monitoring, early tumors can be detected in time, and minimally invasive surgery without incision can be applied to remove them and avoid tumors from progressing to “cancer” again. However, through regular follow-up monitoring, early tumors can be detected in time and removed by minimally invasive surgery without surgery to prevent them from progressing to the level of “cancer”. In layman’s terms, we cannot prevent tumor from sprouting again, but we can prevent it from growing again! The recommended protocol for monitoring colorectal cancer after surgery is as follows: 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. Monitoring of CEA, CA19-9, once every 3-6 months for 2 years, then once every 6 months for a total of 5 years, and annually after 5 years Abdominal/pelvic ultrasound, chest radiograph every 3-6 months for 2 years, then every 6 months for a total of 5 years, and annually after 5 years CT or MRI of the abdomen/pelvis once a year. Postoperative colonoscopy within 1 year, if abnormal, review within 1 year; if no polyps are seen, review within 3 years; then once every 5 years, resection is recommended for any colorectal adenoma that appears on follow-up examinations.6. PET-CT is not a routinely recommended test. There are several other points worth focusing on: 1. After 2-3 months postoperatively, an enhanced scan of the operative field and liver can be performed, which is useful as a reference standard for postoperative imaging. This is important! Without this reference standard, even if there is a CT-visible recurrent foci or metastases, it is difficult for the radiologist to distinguish whether it is a post-operative change or a lesion, and it is still necessary to wait for the lesion to change again before making a conclusion. Both may delay the disease, and it is also a very painful ordeal for the patient and family while waiting for observation. With early postoperative CT scan results, it will be beneficial for radiologists to confirm recurrent or metastatic lesions at an earlier stage. 2. It is also worth noting that among colorectal tumor patients, a few of them have certain defects in their genes and are prone to other tumors, or even rarer patients with multiple tumor syndrome. Therefore, attention should also be paid to remind patients to pay attention to the screening of other tumors during the postoperative follow-up. For example, breast tumors, ovarian tumors, etc. In men, because the urinary function can be affected after rectal surgery, but the early examination of prostate tumor should not be ignored because of this. 3. For patients who have polyps in the colon outside the scope of surgical resection or who have not completed full colonoscopy due to obstruction before surgery, it is advisable to perform colonoscopy about 3 months after recovery to avoid delaying the disease. Preoperative CT examination may not necessarily detect small tumor lesions upstream of the obstruction, so even if no other intestinal segment tumor is detected during preoperative evaluation, postoperative colonoscopy should still be performed.