EGFR and lung cancer: Eastern Cooperative Oncology Group (ECOG) PS three refers to a state in which a patient can perform only limited self-care and spends more than 50% of the day in bed or in a chair. Notably, the effectiveness of molecular-targeted therapies for epidermal growth factor receptor (EGFR) gene mutations or anaplastic lymphoma kinase (ALK) gene rearrangements in lung cancer patients with low PS has been reported in clinical trials [2,3].