Meta-Analysis of Predictive Value of Ki-67 before Neoadjuvant Chemotherapy in Breast Cancer Patients

Abstract Background Breast cancer is the second most common malignancy among female patients. Early breast cancer is considered potentially curable. Immunohistochemistry has an important role in the pathology of breast disease. It is widely used to localize specifically proteins in cells and tissues. Ki-67, a marker of cell proliferation, is a specific nuclear antigen expressed in all phases of the cell cycle, which can be readily detected using immunohistochemistry methods. Many guidelines and international groups concluded that measurement of Ki-67 could be important both in standard clinical practice and within clinical trials. Objective To clarify relation between expression of Ki67 and response of malignant cells to neoadjuvant chemotherapy in breast cancer. Methods The search was directed through PubMed / MEDLINE, Scopes, Web of science, and the Cochrane Library for information from inception to July 1, 2022, with a combination of the following terms: “Ki-67”, “breast cancer” and “NCT”. More searches by Google Scholar have been used to supplement the search with the sites mentioned above. Abstract-based eligibility studies were obtained, and the manuscripts were fully reviewed. Report bibliographies that meet the eligibility criteria were reviewed for further studies. Results A recently published meta-analysis reported that a high Ki-67 level was associated with a high pCR rate. Our results demonstrate that patients with a Ki- 67 are more sensitive to NCT, have higher pCR rates, and benefit more from NCT compared to those with a low Ki-67. However, it remains unclear whether other factors such as therapy regimens and cycles of NCT, the clinical stage, and tumor location have an impact on Ki-67-based health outcomes. Conclusion The meta-analysis reported here demonstrates that pretherapeutic Ki-67 is associated with pCR in breast cancer patients undergoing neo-adjuvant chemotherapy.