Correlation Of Ki67 And Her2 Expression With Histopathological Grading Of Breast Cancer

Breast cancer is one of the most common types of cancer in women worldwide, including in Indonesia. Biomarker assessments, such as Ki-67 and HER2, have significant prognostic and predictive value in determining tumour aggressiveness and guiding therapy options. Histopathological grading reflects the degree of cancer cell differentiation and plays a role in determining prognosis. This study aimed to determine the correlation between Ki67 and HER2 expression and histopathological grading of breast cancer in women. Methods: This study used an observational analytical design with a cross-sectional approach. Samples were taken from female patients diagnosed with invasive breast cancer who underwent biopsy or mastectomy at one national referral hospital. Ki-67 and HER2 expression were analysed using immunohistochemistry, while histopathological grading was assessed using the Nottingham Prognostic Index (NPI) grading system. Results: The most cases of breast cancer were in the 51-60 years age group, namely 42 respondents (29.6%). Grade 3 breast cancer was the most common, namely 63 respondents (44.5%). Estrogen receptor (ER) results were positive in 89 respondents (62.7%), and negative in 53 respondents (37.3%). In the progesterone receptor (PR) positive results, 81 respondents (57%) were identified, while 61 respondents (43%) had negative results. HER2 Neu results were positive in 54 respondents (38%), negative in 62 respondents (43.7%), and equivocal in 26 respondents (18.3%). Ki-67 was most frequently positive in results/proliferation >20%, with 80 respondents (62.5%), and in negative results/proliferation <20%, with 46 respondents (35.9%). There were 2 respondents (1.6%) in whom Ki-67 was not detected. Ki67 expression in histopathological grading of breast cancer, especially in grade 3, with a p-value of 0.002 (p <0.005) and in grade 2 with a value of 0.003. In contrast, the p-value results for HER2 on histopathological grading of breast cancer did not show significant results in grades 1 (p = 0.051), 2 (p = 0.006), and 3 (p = 0.005), with p-values greater than 0.005. Conclusion: A significant correlation exists between Ki-67 and histopathological grading, whereas no significant correlation is found between HER2 and histopathological grading of breast cancer.