First-Line Afatinib in Patients Aged 75 or Older With Advanced Non-Small Cell Lung Cancer Harboring EGFR Mutation -Multicenter study on the Pharmacokinetics and pharmacogenetics of Afatinib-

INTERVENTION: afatinib CONDITION: patients aged 75 or older with advanced non small cell lung cancer harboring EGFR mutation PRIMARY OUTCOME: response rate SECONDARY OUTCOME: disease control rate; progression free survival; overall survival; Adverse events; Quality of life; PK/PGx INCLUSION CRITERIA: 1)Histlogically or cytologically confirmed EGFR mutation positive non small cell lung cancer(NSCLC) 2)Unresectable and metastatic NSCLC 3)Harboring sensitive EGFR mutation 4)Patients who have never treated with EGFR‐TKI and cytotoxic chemotherapy. 5)More than 75 years old 6)Performance Status (ECOG) 0‐1 7)Measurable lesion for RECIST(version 1.1) 8)Adequate organ functions 9)Life expectancy over 3 months 10)Written informed consent