This is a randomized, open label, parallel group, multi-centre, phase II study of progression free survival, comparing oral ZD1839 (IRESSA™) (250 mg tablet once daily) to vinorelbine 30 mg/m2 infusion on days 1 and 8 of a 21-day cycle) in chemonaïve, elderly patients with locally advanced (stage IIIB) or metastatic (stage IV) non-small cell lung cancer.

Inclusion Criteria:

• Histologically confirmed NSCLC and willing to provide paraffin embedded tumour tissue
• NSCLC - locally advanced (Stage IIIB) or metastatic (stage IV) disease, not amenable to curative surgery or radiotherapy chemonaïve, life expectancy of 12 weeks
• WHO Performance status <= 2

Exclusion Criteria:

• Newly diagnosed CNS metastases
• Less than 4 weeks since completion of radiotherapy or persistence of any radiotherapy related toxicity.
• Hypersensitivity to ZD1839 or intravenous vinorelbine
• Prior treatment with EGFR inhibitors
• Other co-existing malignancies
• ALT/AST >2.5 x ULRR
• ANC < 2.0 x 10^9/L or platelets < 100 x 10^9/L