Ki-67 Expression in Breast Cancer: Association with Molecular Classification and Prognostic Indicators

Abstract

Introduction: Breast cancer is the most common malignancy in female and the second most common cause of death
in women. Prognostic factors are essential in identifying high-risk patients, where adjuvant therapy can improve
outcomes. Ki-67, a potential marker of breast cancer, has gained importance recently for predicting the responsiveness to
chemotherapy. Different Molecular subtypes (Luminal A, Luminal B, HER2-enriched, Triple-negative/Basal-like) exhibit
diverse proliferative activities, influencing therapeutic strategies and prognostic assessments. Histopathological grading
further underscored tumour aggressiveness, particularly in HER2-enriched and Triple-negative/Basal-like subtypes with
elevated Ki67 levels. Aims/Objectives: To evaluate the association of Ki-67 proliferative index with molecular subtypes
& clinicopathological prognostic parameters in breast carcinoma.
Materials and Methods: This is a retrospective study conducted between January 2024 and December 2025 .Ki-67
expression was assessed in 45 cases of biopsy-proven primary breast carcinoma in patients , who underwent radical
or modified radical mastectomy . Association with other prognostic parameters ( tumour histological type, grade, and
lymph node metastasis,ER PR,HER2 ,P53 & molecular subtypes), was evaluated .Statistical analysis was done by Chi
square test and a p value of <0.05 was taken as significant.
Results: Increased Ki-67 expression is seen with high tumour grade, lymph node metastasis, HER2 positivity, and P53
mutations. Conversely, it has a strong inverse relationship with ER/PR receptors .Ki-67 expression was not significantly
related to age, tumour size, or specific histological subtype.
Conclusions: By incorporating proliferative index into routine histology reporting can guide clinicians for prediction
of disease progression and management, therefore can determine survival rate and overall patient outcomes.