Discrepancies between ALK protein disruption and occurrence of ALK gene rearrangement in Polish NSCLC patients

Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor ( EGFR ) mutations or anaplastic lymphoma kinase ( ALK ) rearrangement are predisposed to molecularly targeted therapies. Proper diagnostic is crucial for quick and correct patients qualification to optimal treatment method. Genetic tests to detect predictive factors could be performed sequentially. After excluding EGFR mutations, abnormal ALK protein expression should be tested using immunohistochemistry (IHC) method. In patients with disrupted ALK expression, the rearrangement of the ALK gene should be confirmed by FISH method. Despite few years of experience in analysis of these predictive factors, there are still problems in interpretation of diagnostic tests results. Especially, some recommendations for ALK IHC diagnosis are not precise.