Correlation between Risk Factors and Protein Expression of ER, PR, and HER-2 in Breast Cancer Patients: A Population-Based Study in Makassar Indonesia

Background: Breast cancer is a condition characterized by abnormal and uncontrollable growth of cells in breast tissue. According to Global Cancer Statistics 2020, it ranks as the leading cause of female cancer mortality. The disease has four subtypes defined by protein expression, namely Luminal A (ER/PR (+), HER2 (-)), Luminal B (ER/PR (+), HER2 (+)), triple-negative/basal-like (ER, PR, HER2 (-)), and HER2-enriched (ER (-), PR (-), HER2 (+)), each with distinct characteristics influenced by various risk factors. Therefore, this study aimed to explore the correlation between breast cancer risk factors and protein expression of ER, PR, and HER2. Methods: The cross-sectional analytical study was conducted in Makassar, Indonesia, using secondary data from 259 breast cancer patients. Information on ER, PR, HER2 expression, and patient risk factors such as age, history of hormonal contraceptive use, and family history of breast cancer were extracted from medical records and subjected to statistical analysis using the Chi-square test, with significance set at p < 0.05. Results: The results showed that there was a significant correlation between age ≥ 40 years and the expression of ER, PR, and HER2 (p < 0.005). However, no significant correlations were observed between family history and hormonal contraceptive use with ER, PR, and HER2 expression. Conclusions: This study established a meaningful correlation between risk factors of age and breast cancer subtypes based on ER, PR, and HER2 expression.