Ki67 index of 20% can not judge whether it is serious or not, we need to refer to other indexes, such as the stage and grading of the tumor. Ki67 is a nuclear proliferation antigen, commonly used as a tumor marker, mainly to see the proliferation activity of the tumor, the higher the Ki67 positive index, the higher the proliferation activity of the tumor, and the higher the degree of malignancy, but the severity of the tumor can not be judged by the Ki67 alone, which is only a reference, but also depends on the staging and grading of the tumor. Ki67 index can assist diagnosis and provide prognostic reference, reaching 20% is usually for malignant tumors, but we cannot only give prognostic guidance to patients through Ki67 positive index, but also combine with other indexes, such as the differentiation degree of the tumor and its staging. For example, in early stage cancer, even if the Ki67 positive index is very high, it is not serious. If the malignant tumor is in advanced stage and the Ki67 index is not high, it is also more serious. With 20% Ki67 index, it is recommended to consult a doctor, who will make an assessment based on the specific condition.