Discordance of HER2 expression in primary breast cancer and related axillary lymph node metastasis

Introduction: Over-expression of Her-2 can be an underlying reason for breast cancer (BC). Her-2 expression in metastatic auxiliary lymph nodes of BC patients can affect disease management significantly, as under-estimation of Her-2 expression in lymph nodes of BC patients influences patients life-expectancy negatively. The aim of current study is to evaluate Her-2 expression in primary breast cancer, its accordance with metastatic auxiliary lymph nodes and also to assess this association with some prognostic factors. Methods: This is a cross-sectional study on 70 patients with breast cancer. Age, number of involved lymph nodes, Her-2, ER and PR expression and in case of Her-2 expression, its grade in primary breast cancer were recorded. Her-2 expression was evaluated in the metastatic auxiliary lymph node by immunohistochemistry method. Obtained data were analyzed with IBM SPSS 22 United States. Descriptive data are reported in mean± standard deviation. P-value of less than 0.05 was considered significant. Results: 48.6% of samples showed discordance of primary BC and lymph node metastasis. Our study found positive conversion in 12.5% of patients who has primary BC negative results with positive metastatic lymph nodes and 42.1% of negative conversion. In this study, Her2 concordance was not in association neither with patients age nor primary tumor grade. Lower number of metastatic lymph nodes was significantly associated with Her-2 expression concordance (P-value-0.01). Conclusion: In current study, we found high rate of discordance of Her2 expression in primary breast cancer with metastatic lymph nodes. The number of metastatic lymph nodes affected Her-2 expression concordance diversely.