STUDY ON HER2 STATUS AND RELATIONSHIP WITH PROGNOSTIC FACTORS IN INVASIVE BREAST CARCINOMA

Background: To select patients with targeted breast cancer need to accurately determine the status of HER2 gene amplification. Therefore, HER2 gene amplification should be determined by in situ hybridization (ISH) for all of cases which HER2 positive (2+) by Immunohistochemistry (IHC) staining. Our study aims to apply IHC and DISH to detect HER2 status and relationship with prognostic factors in breast cancer. Subjects and research methods: Cross-sectional descriptive study; 92 patients were diagnosed with invasive breast carcinoma at Hue University Hospital and Hue Central Hospital. IHC and DISH are performed on the Benchmark machines (Ventana) of Roche Diagnostics. Molecular subtypes based on the classification of Saint Gallen (2011). Results: Tumor is usually located in the right breast (53.3%); tumor size > 2-5cm (46.7%); Invasive carcinoma not otherwise specified (73.9%); lymph node metastasis 59.8%, histologic grade 2 (60.3%); disease stage II (51.1%). ER (+) 42.4%, PR (+) 41.3%, HER2 (+) 34.8%, Ki67 (+) 59.8% of cases. The most common molecular subtype of breast cancer is Luminal B (28.3%). HER2 gene amplified by DISH in HER2 (2+) 46.2%, HER2 (3+) by 100%. HER2 gene amplification is associated with HER2 protein expression, molecular subtypes; There is no relationship with the disease stage. Conclusion: In addition to immunohistochemistry, gene amplification with DISH is useful for determining the status of the HER2 gene and supporting the accurate grouping molecular subtypes of breast cancer and target therapy. 34.8% HER2 positive by IHC staining; HER2 gene amplified by DISH in 46.2% of HER2 (2+) cases. There are relationship between the HER2 gene amplified and HER2 protein expression, molecular subtypes in invasive breast carcinoma. Key words: invasive breast cancer, immunohistochemistry, histologic grade, disease stage, molecular subtypes, Dual In Situ Hybridization, DISH