Aim: The human epidermal growth factor receptor HER-2/neu (HER2) gene is a proto-oncogene involved in the signal transduction pathways leading to cell growth and differentiation. The present study focused on the clinical significance of the expression of HER2 in non-small cell lung cancer (NSCLC).
Patients and methods: Consecutive specimens of 159 adenocarcinomas and 77 squamous cell carcinomas, from patients who had been treated by complete resection of NSCLC in our department between 2003 and 2005, were studied. The HER2 expression was evaluated by immunohistochemical staining with score of membranous staining being 0=none, 1=weak, 2=10-30% cells, 3≥30% cells stained.
Results: The staining scores in adenocarcinoma were 0 in 121 patients (76.1%), 1 in 16 (10.0%), 2 in 17 (10.7%), and 3 in 5 patients (3.1%). The HER2 expression scores in squamous cell carcinoma were 0 in 74 patients (96.1%), 1 in 1 (1.2%), 2 in 1 (1.2%), and 3 in 1 patient (1.2%). The postoperative 5-year survival rate of patients with adenocarcinoma according to the expression of HER2 scores 0, 1, 2 and 3 was 75.3%, 77.8%, 76.5% and 20.0%, respectively. Patients with adenocarcinoma with score 3 staining had a significantly unfavorable prognosis compared to those with staining scores of 0-2 (p=0.0216).
Conclusion: HER2 overexpression (score 3) in adenocaricinoma was a significantly unfavorable prognostic factor. Since the number of NSCLC patients with HER2 overexpression was small, further investigations will be necessary to clarify the efficacy of molecular targeted therapy for this subgroup.