Therefore, it could simultaneously reflect heterogeneity within a tumor31, 38, 39 as well as of disseminated lesions.40, 41, 42 Therefore, single tumor tissue biopsies may differ in mutational spectrums due to heterogeneity,43, 44 while circulating tumor DNA analysis may detect missing mutations in the corresponding tissue samples.38, 40, 45 Hence, detection of EGFR mutations in circulating tumor DNA could more comprehensively reflect the disease reality of the patients with NSCLC and guide targeted treatments. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.