HER3 expression in patients with primary colorectal cancer and corresponding lymph node metastases related to clinical outcome.

ABSTRACT

AIM: To evaluate the expression and prognostic value of the epidermal growth factor receptor HER3 in patients with primary colorectal cancer (CRC) and corresponding lymph node metastases. PATIENT AND METHODS: HER3 expression was analysed immunohistochemically (IHC) in primary tumours and in corresponding lymph node metastases from 236 patients with stage II and III CRC. In 58 primary tumours, fluorescence in situ hybridisation (FISH) detection was performed. RESULTS: HER3 was detected at high frequency in the cell membrane. Seventy percent of the primary tumours had a high HER3 expression compared to 75% in the lymph node metastases. HER3 expression in the primary tumour was an independent prognostic factor for overall survival in the entire group of patients (p=0.026) and in the subgroup of patients with colon cancer stage II (p=0.030). A high HER3 expression in the primary tumour was associated with worse clinical outcome. The expression of HER3 was homogenous within the primary tumour (r=0.9, p<0.0001) and correlated with the HER3 expression in corresponding lymph node metastases (r=0.6, p<0.0001). No gene amplification with respect to HER3 was seen in primary tumours using FISH analysis. CONCLUSION: A high HER3 expression was found in 70% of the primary CRC tumours and in 75% of the corresponding lymph node metastases. HER3 expression in the tumour was an independent prognostic factor, where a high HER3 expression was associated with worse clinical outcome. There was a correlation in HER3 expression between primary tumour and corresponding lymph node metastases.