MKI67 and breast cancer: Multiple molecular markers such as Topo, ER, PR, Cerb B-2 and Ki67 are all involved in the occurrence and development of breast cancer, and their positive expression is of great significance to clinical medication and prognosis prediction.8 TOPO existing in cell nucleus can change the topological forms of DNA (I and II) by catalyzing DNA breakage and binding of DNA chain.9 Topo II, also called gyrase, includes two isozymes, i.e., α and β.