Objective: To evaluate the sensitivity and specificity of fully automated immunohistochemistry (IHC), with comparison to FISH, in the detection of EML4-ALK rearrangement in lung adenocarcinoma (ADC); and the use of IHC as a pre-screening tool.
Methods: A total of 404 paraffin-embedded NSCLC samples from surgical resections were tested by IHC with Ventana anti-ALK rabbit monoclonal antibody (D5F3) and ultrasensitive detection kit. ALK rearrangement was further confirmed by FISH.
Results: Twenty-nine of 404 lung ADCs (7.2%) were positive for ALK by IHC. ALK positive tumor cells demonstrated strong and diffused granular cytoplasmic staining. All the ALK IHC-positive cases were confirmed to harbor ALK rearrangement by FISH. None of the ALK IHC-negative cases was FISH-positive.
Conclusions: IHC can effectively detect ALK rearrangement in lung cancer. It may provide a reliable and cost-effective diagnostic approach in routine pathologic laboratories for the identification of suitable candidates for ALK-targeted therapy.