Ki67 is an immunohistochemical stain that represents a nuclear proliferation index. Ki-67 <5% represents that <5% of cells in all malignant tissues taken in the biopsy are in a growth state, suggesting that the tumor cells are inactive and less malignant in terms of proliferation. Ki-67 is a nuclear antigen in the nucleus associated with cell proliferation, and Ki-67 should have a value of 0 in normal cells. Ki-67 is generally used to determine the benignity or malignancy of tumors, the higher the value of Ki-67 in tumor cells suggests that the malignancy of the tumor is higher.The function of Ki-67 is related to cell division, so the higher the Ki-67 indicates that the proliferation of tumor cells is more active, and the degree of malignancy is higher. The amount of Ki-67 is very closely related to the cell division cycle.Ki-67 is expressed in the G1, S, G2 and M phases of cell division, but after the end of the M phase, Ki67 is degraded very quickly, and cells in the G0 phase do not express Ki67. In normal tissues, the vast majority of cells are in the G0 phase, i.e., quiescent phase.Ki-67 is generally used to determine the degree of malignancy of a tumor, to assess the prognosis, and to determine whether chemotherapy is sensitive or not. If the Ki-67 index is abnormal, it is recommended to go to the regular hospital to improve the relevant examination or receive diagnosis and treatment, so as to avoid delaying the condition.