Diagnosis of the HER2 gene in breast cancer

Abstract

Introduction: HER2 gene activity in women with breast cancer is important for developing patient treatment plans and improving patient prognosis. Because tanstuzumab, lapatinib, and targeted therapy are used in combination with standard chemotherapy in HER2 overactive breast cancer patients. Currently, there are few studies of this gene in the oncological practice of our country, which forms the basis of our research. Purpose: Our purpose is to determine the level of protein (IHC) and gene amplification (ISH) in the diagnostic algorithm HER2 in women diagnosed with breast cancer in Mongolia. Material and method: The study was conducted on the archives of 30 breast augmentation surgeons diagnosed with breast cancer by the pathology department of the National Cancer Center, registered in 2017-2018. Pathological assessment was performed by immunohistochemical analysis (IHC) using a hemotoxylin-eosin dye on tissue parafÏn enriched with formalin. Immunohistochemical reactions should be assessed in accordance with ASCO / CAP assessment guidelines. In two cases where the HER2 protein was in doubt, or two positive (2 ++) results, and in one case with three positive (3 +++) results confirmed by IHC testing, the genetic activity was determined using in vitro fertilization (ISH). Results: Of the 30 archived materials studied, 9% were positive (+++), 6.6% were doubtful (++), and the rest were negative (+ and -) malignant neoplasms by immunohistochemistry of the HER2 receptor. We ran the IHC test on two questionable samples and one positive sample and found an increase in the HER2 gene in one patient who had doubts (2 ++) and one patient who tested positive (3 +++). Thus, 4 or 13.3% of the 30 samples were positive. Conclusion: Immunohistochemistry showed that 13.3% of the 30 samples were positive, indicating that the number of cases requiring HER2-positive treatment in Mongolia was relatively high. The results of immunohistochemical and hybridization tests show that a complete diagnostic algorithm is required for the diagnosis of breast cancer, which is immunohistochemistry, hybridization and molecular genetics.