Abstract: Objective To investigate the relationship between anaplastic lymphoma kinase (ALK) protein and the pathological features of non-small cell lung cance (NSCLC). Methods The expression of ALK protein in paraffin-embedded specimens of 125 NSCLC patients was detected by VENTANA ALK (D5F3) immunohistochemical method (IHC). ALK protein expression was detected by fluorescence in situ hybridization (FISH). The expression of EML4-ALK fusion gene was analyzed to analyze the relationship between the expression of ALK protein and the clinicopathological features and prognosis of NSCLC. Results The expression of ALK protein was positive in 15 patients (12.0%) in 125 patients. The positive expression of ALK protein was mainly in the cytoplasm and a few in the cell membrane. The positive rate of ALK protein in patients with smoking history was significantly lower than those without smoking history. The positive rate in cancer was significantly higher than that in non-adenocarcinoma, and the positive rate in high-to-differentiated carcinoma was significantly lower than that in poorly-differentiated carcinoma (P<0.05). Kaplan-Meier analysis showed that ALK-positive patients had better prognosis than negative ones (P<0.05). Fifteen ALK protein-positive cases were verified by FISH and 10 cases were FISH positive. Conclusions The expression of ALK protein is closely related to the history of smoking, clinical pathology and tumor differentiation in NSCLC patients. IHC can be used as a reliable ALK screening method to increase the ALK detection rate. FISH detection is of great significance for the diagnosis of ALK protein-positive lung cancer.

Key words: Non-small cell lung cancer, ALK protein,, Survival analysis