(a-g) cfDNA alterations detectable by clinical assay in patients with EGFR mutations. Mutant allele frequency of detected cfDNA alterations are indicated, as is line of therapy and clinical response pre-and post-assay. Computed-tomography (CT) scans of the chest and abdomen are shown, demonstrating sites of metastases (red arrows). Scale bar = 5 cm, ND (no alteration detected). PR (Partial Response), PD (Progressive Disease), SD (Stable Disease). Plasma copy number gain (CNG) of 2.0-2.49 is reported as + and 2.5-4.0 as ++ (see Online Methods).