To determine the benignity and malignancy of a tumor, we should look at the biological behavior of the tumor and the morphological changes of the tumor. Biological behavior refers to the extent of tumor growth, whether there is metastasis, whether there is damage to important organs, and whether there is influence on physiological function. Morphological changes refer to the heterogeneity of the tumor, the degree of difference from the original tissue and the degree of malignancy. Therefore, there is a grading and staging to judge the benignity and malignancy of tumor. According to the malignancy degree of morphological changes of tumor, it is divided into three levels from low to high: Grade I, highly differentiated carcinoma, better differentiation and low malignancy; Grade II, moderately differentiated carcinoma, better differentiation and moderate malignancy; Grade III, poorly differentiated carcinoma, the highest malignancy.