Immunohistochemical expression of HER-2/neu in patients with lung carcinoma and its prognostic significance

Abstract

Background. The HER-2 protein or p185her2 is a membrane receptor with tyrosine kinase activity encoded by HER-2/neu gene. Overexpression of HER-2/neu has been observed in many human cancers, including lung cancer. In the study, the expression of HER-2 protein is determined in the spectrum of lung cancer (adenocarcinoma, squamous cell carcinoma and small cell carcinoma).

Patients and methods. The study population consisted of two groups: 19 patients that had undergone surgical treatment and 10 patients that had undergone fiber-optic bronchoscopy and biopsy for primary diagnosis only. Tissue specimens were neutral formaldehyde-fixed and paraffin-embedded. Standard histochemical and immunohistochemical staining were used for diagnosis. Expression of HER-2/neu protein was determined by immunohistochemical staining with Hercep TestTM (DAKO). The results were graded 0-1 as negative and 2-3 as positive.

Results. Overall incidence of HER-2/neu overexpression was 34.4% (10 of 29). Higher incidence was found in the patients with adenocarcinoma 45.4% (5 of 11). In squamous cell carcinoma and small cell carcinoma, the overexpression incidence was 30.7% (4 of 13) and 20% (1 of 5), respectively. No statistically significant difference was seen given the age and gender. HER-2/neu overexpression was more pronounced in the patients with advanced tumour: all patients with squamous cell carcinoma and HER-2/neu overexpression had stage IIIB and stage IV disease, while 80 % of adenocarcinoma patients with HER-2/neu overexpression had stage IIIA and IIIB disease.

Conclusions. These results are satisfactory and encourage us to continue this work in the follow-up study to evaluate HER-2/neu role as predictive and prognostic factor for the patients with lung cancer.