Expressions and clinical significance of MCM-5 and Ki 67 in breast cancer tissue HUANG Ping, MO Jun-yang, REN Zhan-ping. The Fifth Affiliated Hospital, Guangxi Medical University, Liuzhou 545001, China Corresponding author：HUANG Ping, E-mail:mojunyang2006@163.com Abstract Objective To study the expressions and clinical significance of minichromosome maintenance?5 (MCM?5) and Ki-67 in breast cancer tissue．Methods Immunohistochemistry (SP method) was applied to detect the expression of MCM-5 and Ki-67 genes in tissues from 45 cases of breast cancer after operation from January 2007 to April 2008 at the Fifth Affiliated Hospital of Guangxi Medical University．Results The expression level of MCM-5, Ki-67 was significantly correlated with clinical stage (P＜0.05) and axillary lymph node metastases (P＜0.01). The expression level of MCM-5 and Ki-67 in no lymph node metastasis cases was higher than those in lymph node metastasis cases significantly. The expression of Ki-67 was not correlated with ER and PR status. Conclusion The gene products of MCM?5and Ki-67 play a key role in the oncogenesis and development of breast cancer. Their expression could be useful indexes to assess the malignant level and clinical prognosis of breast cancer. The expression of MCM?5 may be a independent prognostic factor of postoperative survival for patients with breast cancer.The combined use of the above markers may be helpful in making a better estimation of prognosis.