Inclusion Criteria:

• Recurrent or progressive Non-Small Cell Lung Cancer stage IV or IIIB patients after chemotherapy following gefitinib failure
• Male and female patients aged over 18 years
• WHO performance status 0-2 (those with performance status 2 must have been stable with no deterioration over the previous 2 weeks)
• Had at least stable disease with previous Gefitinib treatment
• Had at least one anticancer agent therapy after gefitinib failure ;Following treatment with another EGFR TKIs (erlotinib) or other TKIs should not be included in anticancer agent therapy.
• The current approved indication of Gefitinib is 2nd or 3rd line monotherapy for recurrent or metastatic NSCLC. However, in practice with off-label indication, it can also be used as a 1st line treatment at the patient's own expenses. Thus, in this trial gefitinib retreatment will be 3rd line or more.
• Measurable lesion according to RECIST with at least one measurable lesion not previously irradiated, unless disease progression has been documented at that site.
• Provision of written informed consent
• Life expectancy of at least 12 weeks

Exclusion Criteria:

• Evidence of clinically active Interstitial Lung Diseases (Patients with chronic, stable, radiographic changes who are asymptomatic need not be excluded)
• Expected life expectancy less than 2 months
• Known severe hypersensitivity to gefitinib or any of the excipients of this product
• Any unresolved chronic toxicity greater that CTC grade 2 from previous anticancer therapy
• As judged by the investigator, any evidence of severe or uncontrolled systemic disease (e.g. unstable or uncompensated respiratory, cardiac, hepatic, or renal disease)
• Serum bilirubin greater than 3 times the upper limit of reference range (ULRR)
• Aspartate aminotransferase (AST/SGOT) or alanine aminotransferase (ALT/SGPT) ≥ 2.5 x ULN if no demonstrable liver metastases (or >5 x in presence of liver metastases)
• Evidence of any other significant clinical disorder or laboratory finding that makes it undesirable for the subject to participate in the study
• Pregnancy or breast-feeding women (women of child¬bearing potential). Women of childbearing potential must practice acceptable methods of birth control to prevent pregnancy.
• Newly diagnosed CNS metastases that have not yet been treated with surgery and/or radiation. Patients with previously diagnosed and treated CNS metastases or spinal cord compression may be considered if they have evidence of clinically stable disease (no steroid therapy or steroid dose being tapered) for at least 2 weeks