EVALUATION OF IMMUNOHISTOCHEMICAL BIOMARKERS (KI-67, P53, AND HER2) IN BREAST CARCINOMA: CORRELATION WITH TUMOR GRADE AND PROGNOSTIC OUTCOMES

Abstract

Background: Breast carcinoma had remained one of the most common malignancies affecting women, and accurate assessment of tumor biology had been essential for predicting disease behavior and guiding treatment. Immunohistochemical biomarkers such as Ki-67, p53, and HER2 had provided valuable information regarding cellular proliferation, tumor suppressor abnormalities, and receptor status. Their association with histopathological tumor grade had been clinically relevant for prognostic assessment. Aim: The study aimed to evaluate the expression patterns of Ki-67, p53, and HER2 in breast carcinoma and to determine their correlation with histopathological tumor grade and prognostic outcomes. Methods: This hospital-based observational study was conducted at Mayo Hospital, Lahore, from August 2025 to January 2026. A total of 80 patients with histopathologically confirmed breast carcinoma were included. Tumor specimens were evaluated for histological grade, while immunohistochemical staining was performed for Ki-67, p53, and HER2. Ki-67 expression was assessed according to the percentage of positively stained tumor cells, whereas p53 expression was evaluated based on staining intensity and proportion of positive cells. HER2 expression was interpreted according to established immunohistochemical scoring criteria. Associations between biomarker expression, tumor grade, and recorded prognostic parameters were analyzed statistically. Results: Among the 80 breast carcinoma cases, higher tumor grades were associated with increased Ki-67 proliferative activity and greater p53 expression. HER2 positivity was also observed more frequently among higher-grade tumors. Tumors demonstrating high Ki-67 expression showed a greater proportion of aggressive histopathological features, while p53 overexpression was associated with poorer tumor differentiation. HER2 positive tumors demonstrated higher-grade pathological characteristics compared with HER2-negative tumors. The combined assessment of Ki-67, p53, and HER2 provided additional information regarding tumor biological aggressiveness and prognostic characteristics. Conclusion: The study demonstrated that Ki-67, p53, and HER2 immunohistochemical biomarkers had shown meaningful associations with tumor grade and prognostic characteristics in breast carcinoma. Their combined evaluation alongside conventional histopathological grading had provided useful information for assessing tumor aggressiveness and supporting prognostic stratification.