Unfortunately, the current FISH diagnostic assays do not produce clear “black or white” results but instead frequently give scope for the interpretation of assay results, leading to an unacceptable high error rate with the consequence of false therapies, especially as current studies show that the available assays do not detect all known variants of ALK fusions occurring in NSCLC [58,59,60]. This evidence concerns the gene ALK and non-small cell lung carcinoma.