EcDNA-encoded genes (e.g., MYC, MYCN, EGFR, Platelet-derived growth factor receptor alpha (PDGFRA), and epithelial transition (MET) are amplified in both primary and recurrent cancers, connecting the ecDNA to the evaluability of cancer cells under the selection pressure of the tumor microenvironment and therapeutic circumstance [85]. The gene discussed is MYC; the disease is cancer.