It is a prognostic test that detects the risk of developing lung cancer by analyzing the expression of RNA in exosomes derived from plasma, namely EML4‐ALK, which is the outcome of the fusion of two genes known as echinoderm microtubule‐associated protein‐like 4 (EML4) and anaplastic lymphoma kinase (ALK).[145]. The gene discussed is EML4; the disease is lung cancer.