Lack of prognostic implications of HER‐2/neu abnormalities in 345 stage I nonsmall cell carcinomas (NSCLC) and 207 stage I–III neuroendocrine tumours (NET) of the lung

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Abstract
HER‐2/neu oncogene activation by either gene amplification and/or protein overexpression has been documented in several human malignancies. Irrespective of protein overexpression, HER‐2/neu gene amplification is rare in lung cancer and studies on its prevalence and clinicopathological implications in early stage nonsmall cell lung cancer (NCSLC) and neuroendocrine tumours (NET) of the lung are lacking. We evaluated HER‐2/neu abnormalities in 345 Stage I NSCLC and 207 Stage I‐III NET of the lung of all the diverse histological types, by using immunohistochemistry and fluorescent in situ hybridization in selected cases. Overall, HER‐2/neu immunoreactivity was detected in 23% of 345 NSCLC and in 7% of 207 NET. Gene amplification was seen in only 7 (7.4%) of the immunoreactive tumours, with high‐level amplification (HER‐2/neu gene to chromosome 17 ratio > 4.0) in 3 adenocarcinomas, 1 squamous‐cell carcinoma and 1 large‐cell neuroendocrine carcinoma (LCNEC), and low‐level amplification (HER‐2/neu gene to chromosome 17 ratio from 2.0 to 4.0) in 1 squamous‐cell carcinoma and 1 LCNEC. None of tested carcinoids and SCLC showed gene amplification. All but 1 gene amplified case exhibited 2+ or 3+ membrane labeling. No relationship was found between gene amplification or protein overexpression and patients' survival or other clinicopathological variables. HER‐2/neu gene amplification and protein overexpression are not closely correlated in lung carcinomas and do not bear any prognostic implication. Among neuroendocrine tumours, LCNEC show a slightly higher prevalence of either HER‐2/neu gene amplification or protein overexpression.