Prognostic and predictive significance of Ki67 dynamic change during preoperative endocrine therapy in breast cancer patients

Currently, there is a marked tendency towards improvement of early detection of breast cancer that allows patients at extremely low risk for developing recurrent disease to be identified. Therefore, it is necessary to search for biological markers of unfavorable prognosis for patients with hormone-dependent breast cancer. In order to introduce these markers into routine clinical practice, they should be validated in well-designed clinical studies, provide additional predictive information and be easily reproducible. The standard immunohistochemical parameters (estrogen and progesterone receptors and Ki67 cell proliferation index) can be served as these markers. However, the dynamic changes in these parameters during hormone therapy rather than their initial expression levels in the tumor are of great significance for the individualized hormone therapy.