Clinicopathological Characteristics of HER2-Positive Breast Cancer at H. Adam Malik General Hospital

Background: Human Epidermal Growth Factor Receptor 2 (HER2)–positive breast cancer is an aggressive molecular subtype associated with high proliferation rates, early metastasis, and unfavorable prognosis (Ellingjord-Dale et al., 2022; Oh & Bang, 2020). Data describing this subtype in Indonesia, particularly in Sumatera Utara, remain limited. Objective: To describe the demographic and clinicopathological characteristics of HER2-positive breast cancer patients treated at RSUP H. Adam Malik, Medan. Methods: A descriptive observational study was conducted using retrospective medical record data of HER2-positive breast cancer patients (Ma et al., 2022). Variables analyzed included demographic characteristics, histological type, tumor size, histological grade, lymph node involvement, distant metastasis, lymphovascular invasion, tumor-infiltrating lymphocytes (TILs), and Ki-67 index. Data were analyzed descriptively and presented as mean ± standard deviation and frequency distributions. Results: A total of 140 HER2-positive breast cancer patients were included. The mean age was 48.5 ± 10.2 years (range 37–65). Most patients were aged 41–50 years (34.2%) and were female (100%). Invasive ductal carcinoma was the predominant histological type (86.8%). Tumor size was most frequently classified as T2 (50.0%), and high histological grade (grade III) was observed in 56.6% of cases. Lymph node involvement was present in 66.9%, while distant metastasis was identified in 39.2%. Lymphovascular invasion was found in 58.8%, and a high Ki-67 index (>20%) was observed in 55.9%. Conclusion: HER2-positive breast cancer patients at RSUP H. Adam Malik commonly present at a relatively young age with advanced and aggressive clinicopathological features. These findings highlight the importance of early detection and comprehensive management strategies for HER2-positive breast cancer in Indonesia (Loibl & Gianni, 2022).