Four patients’ CTCs (n = 4/7, 57.1%) harbored more mutation overlap with the primary lung tumors, including a nonsense mutation of a tumor-suppressor gene RRAD in P1, cancer-driver genes of POLR2A and TP53 in P5, chromatin-remodeling oncogenes BPTF and ELP3 in P6, a stem cell–related gene ORC1, and a drug-resistant gene ST6GAL2 in P9 (Figure 3 and Supplementary Table 3). The gene discussed is POLR2A; the disease is cancer.