Evaluation Of Human Epidermal Growth Factor Receptor 2 Oncoprotein in Serum and Tissue Samples of Women with Newly Diagnosed Breast Cancer

Background: The Human Epidermal Growth Factor Receptor 2 (HER2) proto-oncogene is extensively studied in breast cancer patients. Identifying patients who would benefit from HER2-targeted therapy requires assessing HER2 overexpression.Objective: This study evaluated HER2 expression in tissue through Immunohistochemistry (IHC) and in blood through Enzyme-Linked Immunosorbent Assay (ELISA), and its relationship with other tumor characteristics. Methods: This study is a comparative cross-sectional study carried out at the Basra Oncology and Hematology Centre and Basra Hospital for Women and Children- Breast Center from February to December 2022.It involved 44 female patients with newly diagnosed primary breast cancer and 44 control group. Serum HER2 levels were studied by ELISA method. Surgical samples were investigated for the type of carcinoma, tumor size, lymph node metastasis, stage and grade of the tumor and reports of the results were obtained. Also, reports of the tissue HER2 expression were obtained. Results: The study showed that, the median serum HER2 in breast cancer patients was 6.90 ng/mL. The serum HER2 concentration was significantly higher among cases compared to control group (P= 0.030). The serum HER2 was significantly higher among those who were positive for tissue HER2 (P= 0.04) and among those with tumor metastasis (P= 0.038). Conclusions: This study revealed that elevated levels of serum HER2 were correlated with the IHC expression of HER2 in tissue and tumor metastasis. Also, there was a significant increase among patients with breast cancer compared with controls. For this reason, serum HER2 results holds a potential diagnostic tool with the ability to reflect the tumor burden.