Many of these ecDNA species were highly amplified and contained canonical oncogenes (Fig. 1b), supporting the idea that heterogeneous ecDNA sequences can be found in the same tumour and their co-occurrence may provide distinct selective advantages (such as CCND2, EGFR and MDM4 in a glioblastoma sample, and MYC and KRAS in a urothelial bladder carcinoma sample; Extended Data Fig. 1b). This evidence concerns the gene EGFR and neoplasm.