EGFR and cancer: Several Food and Drug Administration (FDA)–approved assays are commercially available for ctDNA-based cancer diagnostics, including a PCR kit for detection of epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer patients (Cobas v2) (24) and a PCR assay measuring methylated SEPT9 in blood to detect CRC (Epi ProColon) (25).