ALK and non-small cell lung carcinoma: The fluorescence in situ hybridization (FISH) assay is recommended for the detection of ALK rearrangements in the US National Comprehensive Cancer Network (NCCN) guideline for NSCLC [1], and this test is still considered the “gold standard”’, whereas immunohistochemistry (IHC) was considered a screening test for this purpose [2, 3].