Utility of Serum HER-2/ neu in Prediction of Tissue HER-2 /neu Status of Primary Breast Cancer

Background: The use of biomarkers has become increasingly important in the diagnosis and treatment of several malignancies, including breast cancer. Among the established biomarkers, receptor tyrosine-protein kinase erbB-2 (HER-2/ neu) has been found to be of a predictive and prognostic role in breast cancer patients. Method: 94 patients with primary breast cancer were enrolled in our prospective study between 2016 and 2017. 5 cc clot blood samples were taken for serum HER- 2/neu testing at the time of diagnosis of breast cancer. The patients’ demographic data, tumor characteristics, including tumor size, tumor grade, presence of lymph node involvement, and stage, hormone receptor, and tissue HER-2/neu status of the subjects were recorded following tumor removal. Results: All of the patients were female with the age range of 27 to 80 years (the mean of age was 49.66. 36 patients (38.3%) had positive tissue HER-2 results and 58 (61.7%) had negative results. In those with high level serum HER-2 ECD, 28(77.7%) had positive tissue HER-2 and 8(22.2%) had negative results. Moreover, in the patients with low level serum HER-2 ECD, 8(13.7%) had positive tissue HER-2 and 50(86.2%) had negative results with the sensitivity of 77.7% and specificity of 86.2%. HER2 ECD levels were highly concordant with tissue HER2 status, with a P value of less than 0.001, which was considered to be statistically significant. Among different clinicopathologic variables, serum and tissue HER-2/nu were significantly correlated with only tumor grade. Conclusion: A significantly increased release of HER2 ECD levels may accurately predict tumor HER2 status as detected with immunohistochemistry and/or in situ hybridizations studies.