HER-2/ neu Protein Expression and Gene Alteration in Stage I-IIIA Non–Small-Cell Lung Cancer: A Study of 140 Cases Using a Combination of High Throughput Tissue Microarray, Immunohistochemistry, and Fluorescent In Situ Hybridization


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Abstract

Regarding HER-2/ neu expression (gene or protein level) in lung cancer, several studies with inconsistent results have been recently reported, partially due to variable techniques used and/or heterogeneous populations examined. The objective of this study was to examine HER-2/ neu expression in a well-defined cohort of non–small-cell lung cancers (NSCLC) and in nonneoplastic lung tissue utilizing a combination of high-density tissue microarray, immunohistochemistry (IHC), and fluorescent in situ hybridization (FISH) under uniform test conditions. One hundred forty stage I-IIIA primary NSCLCs and 38 non-neoplastic lung samples were examined. IHC, using an FDA-approved Hercept monoclonal antibody kit, was performed and HER-2/ neu gene alteration was assessed by FISH. The association of expression of HER-2/ neu with clinicopathologic parameters was analyzed. Ninety-four percent of tumor samples (131/140) were fully interpretable after tissue processing. Twenty-five of them (19%) overexpressed (2+, 3+) HER-2/ neu, while 106 (81%) had no or weak expression. All thirty-four interpretable non-neoplastic lung samples were negative for HER-2/ neu alteration at protein and gene level. HER-2/ neu protein overexpression correlated well with HER-2/ neu gene amplification (r =.83, P < 0.001). HER-2/ neu overexpression was significantly associated with histologic subtype: 19 adenocarcinomas (19/82, 23%) versus 4 squamous cell carcinomas (4/44, 9%) overexpressed Her-2/ neu (P = 0.04). Statistical significance was observed between HER-2/ neu expression and tumor differentiation, with strong positive (3+) expression observed more frequently in poorly differentiated tumors (P = 0.01). Patients with HER-2/ neu abnormalities, particularly HER-2/ neu gene amplification, exhibited a shorter survival (P = 0.043). The statistically significant difference (P < 0.005) between HER-2/ neu alteration in tumor samples(25/131, 19%) and in the nonneoplastic tissue (0/34, 0%) implies that HER-2/ neu may have a role in the carcinogenesis of NSCLC. The findings provide evidence supporting the hypothesis that the HER-2/ neu receptor may represent a useful molecular target in the treatment of NSCLC. The significant association of HER-2/ neu expression and gene amplification with poorly differentiated carcinoma compared with well differentiated carcinoma suggests that HER-2/ neu may be involved in NSCLC tumor evolution. Patients with HER-2/ neu gene amplification and strong positive expression of HER-2/ neu protein showed a strong tendency toward shorter survival.

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