Here, we report the case of a patient with four lung cancers (tumor 1, named T1, in the right middle lobe seven years earlier; tumor 2, named T2, in the left lower lobe; tumor 3 and tumor 4, named T3 and T4, in the left upper lobe) and two tumors (T1 and T2) which shared the mutation in epidermal growth factor receptor (EGFR) L858R/T790M based on targeted multigene sequencing, which indicate that these two tumors might have originated from a common ancestor. The gene discussed is EGFR; the disease is lung cancer.