1. Patients with colorectal cancer are prone to liver metastasis. Liver is a common metastatic organ of malignant tumors, and liver metastasis occurs in 40% of patients with malignant tumors, and the rate of liver metastasis is even higher in patients with colorectal cancer, and clinical research shows that liver metastasis of colorectal cancer can be as high as 60%~71%. A large number of clinical studies and clinical practice show that liver is the most common site of metastasis for colorectal cancer patients, and liver metastasis occurs in about 25%-30% of patients at the same time or within six months of diagnosis of colorectal cancer. And every year worldwide, there are more than one million new cases of colorectal cancer, and more than half of them eventually develop liver metastasis. Liver metastasis of colorectal cancer can be divided into simultaneous liver metastasis and heterochronic liver metastasis. The former refers to the discovery of liver metastasis at the same time as colorectal cancer is discovered, and the interval between the discovery of primary and liver metastases is < 6 months; the liver metastasis after playing bowel cancer surgery, and the interval between the discovery of primary and liver metastases > 6 months is heterochronic liver metastasis, and about 30% ~ 40% of heterochronic liver metastases occur after the so-called radical resection, and 80% occur within 2 years after surgery. Liver metastasis is the main reason affecting the efficacy, prognosis and long-term survival of colorectal cancer patients. 2.Why are colorectal cancer patients prone to liver metastasis? This is a very complicated medical question because liver metastasis of colorectal cancer itself is an extremely complex biological process, the detailed mechanism of which is not completely clear, and micro-metastasis is currently considered as one of the possible causes. From the anatomical point of view, the venous blood flow that drains to the colorectum converges into the portal vein at the first station, that is, into the liver, and the liver sinus is the site of blood return from the gastrointestinal tract. Colorectal cancer is most likely to invade the veins, and the incidence rate can be as high as 20%~30%; once the cancer cells are shed and enter the blood circulation, it is easy to form metastases in the liver. 3.How to diagnose liver metastasis of colorectal cancer? The diagnosis of simultaneous liver metastasis mainly relies on preoperative examination and/or intraoperative exploration, as well as intraoperative biopsy if necessary; while the diagnosis of heterochronic liver metastasis mainly relies on regular follow-up review after surgery. Abnormally elevated serum CEA is 4~10 months earlier than the clinical detection of recurrent metastases, and its positive rate can generally reach more than 70%. Therefore, postoperative patients with colorectal cancer should have their serum CEA reexamined every 2~3 months, which is an effective method for early detection of recurrence and metastases. In addition, determination of CEA in bile and duodenal fluid may also detect liver metastases at an earlier stage. It should be emphasized that there is a lack of new markers that can replace serum CEA. 4.How to treat liver metastasis of colorectal cancer? Unlike other malignant tumors, patients with liver metastases from colorectal cancer must be treated with a positive attitude. If patients with liver metastases from colorectal cancer are not treated, the median survival period is only 5-10 months; if they are given active and effective multidisciplinary comprehensive treatment, the survival period of patients with liver metastases from colorectal cancer will be significantly extended and the quality of life will be significantly improved, in which the 5-year survival rate can reach 20%-40% and the median survival period can be extended to 28-40 months or even longer. At present, the multidisciplinary collaboration (MDT) integrated treatment model, which is widely used in clinical practice, is the best treatment model for patients with liver metastases from colorectal cancer. Only by organically combining the surgical resection of general surgery and liver surgery, chemotherapy and targeted drug therapy of internal medicine, radiofrequency ablation and interventional therapy of interventional medicine, can we create a miracle of treatment and recovery of liver metastasis from colorectal cancer!