Ki67 positivity rate 20% malignancy degree needs to be judged according to the specific tumor type and the determination value of different pathological centers, if it is highly expressed, the degree of malignancy is high. Ki67 antigen positivity rate is a reliable indicator of tumor proliferation activity, the higher the positivity rate, the more active tumor cell proliferation, indicating that the tumor is poorly differentiated, highly malignant, prone to recurrence and metastasis, and has a poor prognosis. The judgment of Ki67 expression is related to the type of tumor. Generally speaking, breast cancer is considered to have high Ki67 expression if it is over 20%~30%; gastric cancer is considered to have high Ki67 expression if it is over 25%, and the specific threshold should be referred to the local pathology center. If the local pathology center determines that 20% of Ki67 positivity is high expression, the degree of malignancy is high; if 20% of Ki67 positivity is low expression, the degree of malignancy is low. Patients are advised to consult with specialized doctors and actively cooperate with the treatment in order to prolong the survival period.