Abstract
BACKGROUND: The fusion (rearrangement) of anaplastic lymphoma kinase (ALK) gene has been identified as an import factor to the tumorigenesis and development of lung cancer. ALK tyrosine kinase inhibitors (ALK-TKIs) have been proved to have good effects to ALK positive lung cancers. The increasement of the relevance ratio of ALK will be very important to patients. The aim of this study is to investigate the clinical pathological features of ALK positive lung cancer, and the roles of immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) in screening and confirming the ALK positive cases in the testing flow of ALK. METHODS: IHC analysis of ALK in tumor specimens was performed on 525 lung cancer patients. 34 cases among them were confirmed by FISH. RESULTS: The positive incidence of ALK by IHC was 5.14% (27/525). The ALK positive patients were significantly younger than ALK negative patients (P<0.05), and femal was predominant (P<0.05). The proportion of solid predominant adenocarcinoma was significantly higher in ALK positive patients (P<0.05). While acinar and lepidic predominant adenocarcinoma were significantly lower in ALK positive patients (P<0.05). FISH was applied in 34 cases. The coincidence rate was increased with the increasement of positive intensity of IHC staining. All the IHC positive cases with or without EGFR mutation must be confirmed by FISH. CONCLUSIONS: IHC is a reliable detection method to screening the ALK in lung cancer, and then enhance the relevance ration. To make a definite diagnosis of ALK positive lung cancer, FISH is a significant detection method.