Concordance of HER2 status in primary tumour and lymph node metastases in patients with esophageal carcinoma.

BACKGROUND Human epidermal growth factor receptor 2 (HER2) is an important prognostic factor in several types of solid tumours. Although HER2 seems not to influence survival in esophageal carcinomas, an impact of the HER2 status of disseminated tumour cells (DTCs) on survival has been shown. The aim of our study was to investigate the significance of the HER2 status in primary esophageal carcinomas and matched lymph node metastases. MATERIALS AND METHODS The HER2 status of primary tumours and matched lymph node metastases were analysed for 158 patients with esophageal carcinoma using immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH). RESULTS The study specimen included 90 adenocarcinomas (AC) and 68 squamous cell carcinomas (SCC). HER2 amplification was found in 12% and overexpression in 8.9% of all primary tumours. HER2 amplification was identical in the primary tumour and lymph node metastases in all AC and in 75% of SCC. Discordant-positive HER2 lymph node status and negative primary tumour status was found in 4.4% of AC and 1.5% of SCC in FISH analyses. No significant associations were found between HER2 amplification/overexpression and overall survival. CONCLUSION HER2 gene status remains highly conserved in metastatic esophageal carcinoma. Discrepancies occur rarely between primary tumour and lymph node metastases and might be due to heterogeneity of the HER2 status of the primary tumour. This could be the reason for heterogeneity of DTCs and may result in metastasis of only a subset of tumour cells.