Correlation Between Ki-67 Expression and Tumor Grade in Breast Cancer: A Cross-Sectional Study

Introduction Ki-67 is a proliferation marker that may correlate with tumor grade in breast cancer. This study explores the association between Ki-67 expression levels and tumor grade in breast cancer patients. Materials and methods This cross-sectional study analyzed Ki-67 expression in tumor samples from 280 breast cancer patients. Ki-67 expression ranged from 5% to 50%, and was categorized alongside tumor grades (Grade 1, Grade 2, Grade 3). Statistical analysis included Spearman correlation and multivariate analysis. Results A significant positive correlation was observed between Ki-67 levels and tumor grades. Mean Ki-67 expression was 15.8% for Grade 1 tumors, 23.2% for Grade 2, and 34.7% for Grade 3 (Spearman correlation coefficient = 0.68, p < 0.001). Multivariate analysis indicated that high Ki-67 expression (≥25%) was independently associated with Grade 3 tumors, especially in triple-negative breast cancers. Conclusions Ki-67 expression strongly correlates with tumor grade and can serve as a prognostic indicator in breast cancer management, particularly in identifying aggressive tumor subtypes.