Systemic spread of rectal cancer firstly needs to analyze whether it is extensive intra-abdominal implantation or distant metastasis of blood, and analyze the cause of local spread. Distant liver metastasis is common in advanced rectal cancer, and the survival time depends on the size of liver tumor and the degree of treatment. If liver metastasis is not treated, the survival rate is 0% in three years, less than 20% in one year, and up to 20% in five years through effective treatment. Lung metastasis after rectal cancer surgery has little impact on the survival time of patients, and can be effectively controlled by chemotherapy.