EGFR and cancer: Patients may suffer from complications after rebiopsy, such as pneumothorax, which is reported to occur in 17%‐27% of patients.24 Also, about 25% of cases provide too few tumor cells or none at all, such that an EGFR mutation assay cannot be conducted.25 A single biopsy specimen may miss cancer heterogeneity, but plasma ctDNA can potentially capture it.26, 27 Many technologies have been developed to improve the sensitivity of tests used to detect genetic mutations in ctDNA.