How to detect cancer metastasis early remains a difficult medical problem at present, and there are no effective detection indicators. The initial stage of metastasis is asymptomatic, which means there is neither subjective discomfort nor reliable early detection tools. However, if the metastases become larger, they can be detected by objective screening tools. This is the reason why cancer patients should be reviewed regularly even after surgery and after chemotherapy is finished. It is to detect metastases as early as possible and intervene early. Many metastases are detected by imaging earlier than the patient’s subjective perception. Taking postoperative gastrointestinal cancer as an example, what indicators can be suggestive for early detection of metastases? First of all, tumor markers, such as CEA, CA199, CA125, etc. are commonly used. If these indicators are abnormal before surgery and return to normal level after treatment, but are found to be abnormal again in the process of review, it should be taken seriously. Although recurrence cannot be judged based on this, if there is a hint of recurrence, imaging examinations (enhanced CT or MRI, and if necessary, whole body PET/CT) should be improved in a timely manner. Especially when the tumor markers are continuously elevated. Secondly, pay attention to the results of the review and the preoperative ones, as well as the comparison of the last review. If a newly discovered lesion is found, it should also be noticed. When the lesion is very small, less than 1cm or even less than 5mm, it is difficult to clarify whether it is metastatic or not with the current examination methods. However, if it was not present on the last review and appears this time, be alert to recurrence. However, it should not be assumed that a newly developed lesion is a recurrent lesion. For example, nodules formed by inflammation in the lung, or nodules formed by liver damage after chemotherapy, or small retroperitoneal lymph nodes, these cannot be considered as recurrence. There is no similarly effective drug for having an effective means to control or avoid metastasis. However, there are several ways to reduce the risk of recurrence: first, standardized treatment is important. From the time of disease diagnosis, it is necessary to enter into a correct treatment strategy or a reasonable treatment route. With a reasonable treatment direction, each specific treatment stage should be completed well, and the result will not be wrong in general. The degree of surgical cure should be good, the scope of surgery should be reasonable, the postoperative adjuvant treatment plan should be reasonable, and the medication should be reasonable, all of which will affect the prognosis; Secondly, the importance of postoperative review should be emphasized again. Sometimes the treatment is scientific and reasonable, but still cannot avoid recurrence. However, what we can do is to detect recurrence early and deal with it in time to minimize the unfavorable factors. Furthermore, patients themselves should change their bad dietary and living habits, adjust their mentality, face it positively, and exercise properly to improve their physical quality, which is also very helpful to reduce recurrence.