Colon cancer moderately differentiated pT4aN0M0 means that the tumor has penetrated the peritoneum or directly invaded other organs, without lymph node metastasis and without distant metastasis. Colon cancer is a common malignant tumor, which can be caused by a variety of factors such as heredity, gene mutation, and poor dietary habits. According to the degree of differentiation of tumor cells, it can be classified into three levels, i.e. high, medium and low differentiation. Among them, the lower the degree of differentiation, the higher the degree of malignancy and the worse the prognosis. According to the development of primary tumor, the degree of lymph node metastasis, and whether distant metastasis occurs, colon cancer can be divided into four stages. Among them, pT4aN0M0 usually represents stage IIB, which is the tumor penetrating the dirty peritoneum, no lymph node metastasis, and no distant metastasis. After active treatment in this period, the five-year survival rate is about 70%~80%.