Gastrointestinal tumors to a certain extent still have the possibility of recurrence and metastasis after surgery, which is the reason why chemotherapy or radiotherapy may still be required even after complete removal of the tumor. Most of the recurrence and metastasis cases are within 3-5 years. During this period, patients and doctors are very careful, strict follow-up and monitoring can find some traces as early as possible, and if feasible, surgery or radiotherapy can be done again, and the treatment effect can be very good. Of course, there will be some suspicions that will eventually be proven to be false information, a matter of cups and arrows that will give people false alarm. Tumor markers are one of the more important indicators in post-operative surveillance. CEA or CA19-9 is elevated again after colorectal cancer surgery, which needs to be alerted, and PET scan can be done if available. Local recurrence, especially hepatic and pulmonary metastases, may show abnormalities of these indicators. In recent years, the effect of comprehensive treatment for colorectal cancer with concurrent liver metastases (all found within 6 months after surgery are considered concurrent) or late liver metastases has been greatly improved, and surgery, chemotherapy, embolization therapy, radiofrequency therapy, plus molecular targeted drug therapy can be considered, and the 5-year survival rate may reach 20%. Many colorectal tumor patients were initially revealed by this indicator as a clue for doctors to detect the problem early. There are some normal people, tumor markers such as CEA may also be mildly elevated, but not persistently increasing. By the same token, if the CEA is stable at a low level in multiple retests after surgery, do not be too nervous if you are not in the middle of treatment, it is not necessarily the cause of tumor. If the CEA is elevated during chemotherapy or further examination, it is possible that there is a tumor, but it is in stable control. Due to the increasing accuracy of imaging, there are often people who find small nodules in the liver, lung and other locations during the follow-up. Whether it is a metastatic lesion often requires multiple reviews and comprehensive evaluation based on dynamic changes, combined with tumor markers and so on. Even if the problem is found, it should be treated calmly and rationally. In fact, there are many examples of false alarm, here are two recent cases. Early last year a patient with colon cancer (pT3N1) developed hoarseness after completing six months of chemotherapy, and a planned lung CT scan revealed a small 3mm nodule in the lung, a nodule that made people very nervous despite a normal CEA. It was reviewed several times every 3 months and determined to be a small nodule due to chronic inflammation of the lung. In a case of rectal cancer earlier this year, the tumor was located as low as the internal anal opening. Because it was considered early stage cancer after precise preoperative evaluation, local excision was done according to the patient’s own choice, and detailed postoperative pathological examination confirmed that it was a highly differentiated adenocarcinoma with local access to the superficial submucosa, and all sections of the tumor were examined to confirm complete excision, and there were no high-risk factors such as vascular lymphovascular invasion. This should be a reliable basis for not requiring additional surgery. Tumor markers were normal at the postoperative 3-month review, but ultrasound exploration plus contrast revealed a new 1-cm hypoechoic mass in the liver, and a further MRI scan of the mass also suspected a new small mass in the liver. Despite my detailed preoperative evaluation and reliable postoperative pathological evidence, he was strongly advised to be managed as a tumor metastasis. This patient was not treated considering his high comorbidity and fortunately, the suspicious mass disappeared on multiple hospital reviews several months thereafter. This case should give some comfort to those suspected patients who are under dynamic observation and luck can be expected! It also shows that whether rectal cancer can preserve the anus, how far from the anal opening is not the key indicator, but the depth of the tumor is.