Is Ki67 Effective as a Prognostic Marker in Node-Positive Breast Cancer Patients?

Ki67 is a proliferation marker commonly assessed by immunohistochemistry in breast cancer, and it has been proposed as a clinical marker for subtype classification, prognosis, and prediction of treatment modalities. Therefore, this study aimed to evaluate the prognostic significance of Ki67 in node-positive breast cancer. A total of 251 cases of axillary lymph node-positive breast cancer were included in the study. Several clinicopathologic factors were collected: age, menopausal status, tumor size, node involvement, tumor grade, estrogen and progesterone receptors, HER2, and Ki67 expression. We analyzed if these parameters could be considered as a prognostic factor. Associations of the Ki67 index with other prognostic factors were evaluated both as continuous and categorical variables. Breast cancer-specific survival analysis of the ki67 level was evaluated with Kaplan–Meier survival curve and Cox regression model adjusted for a known prognostic factor. The majority of patients was alive and without tumor relapse at the moment of the analysis (90.8%). A cutoff of 20% separated tumors into a Ki67-low (n = 94) or Ki67-high group (n = 157). The breast cancer-specific survival was 92. 6% and 89.8% for Ki67-low and Ki67-high groups, respectively. Univariate and multivariate analysis showed that in this lymph node-positive clinical trial, the predictors for breast cancer survival were higher N stage and triple-negative subtype was independent predictors of breast cancer death. Although the Ki67 index is an effective complementary proliferative tool in breast cancers without lymph node involvement in predicting prognosis and survival, our study shows that it is not an effective tool for showing prognosis and survival in node-positive breast cancer patients.