OBJECTIVETo investigate the expression of anaplastic lymphoma kinase (ALK) gene fusion antibody in non-small cell lung cancer (NSCLC) and explore the clinicopathological significance.

METHODSUsing manual immunohistochemistry (IHC) with D5F3 rabbit monoclonal antibody, we detected the expression of ALK gene fusion protein in 519 cases of NSCLC. The relations of ALK fusion protein with the clinical characteristics of the patients and the histological classification of the tumors were analyzed. The expressions of ALK fusion protein were compared between surgical specimens and biopsy samples, and the consistency of manual IHC results was evaluated with the results of a fully automated IHC instrument and fluorescence in situ hybridization (FISH).

RESULTSThe positivity rate of ALK fusion protein was 11.37% (59/519) among the cases detected by manual IHC. The patients tended to have a young age of onset (P=0.048) and most of the tumors were adenocarcinoma. In the surgical specimens, ALK fusion protein was expressed mostly in invasive mucinous adenocarcinoma (P<0.01), and it was a high risk factor of lymph node metastasis [OR=2.188(95%C.I:1.161-4.122)]. No statistical difference was found in the test results of manual IHC between surgical specimens and biopsy samples. The results by manual IHC suggesting a strong expression were consistent with the results by automated IHC and FISH.

CONCLUSIONManual IHC can be reliable for screening ALK fusion arrangement in patients with NSCLC.