OBJECTIVES: The objective of this study was to determine the lifetime cost of treating NSCLC patients with gefitinib. NSCLC is a fatal malignancy that responds poorly to chemotherapy. Best Supportive Care (BSC) is frequently offered when management with anticancer treatments is not feasible. Gefitinib (‘Iressa’) is the first epidermal growth factor receptor tyrosine kinase inhibitor approved for the treatment of patients with locally advanced or metastatic NSCLC. METHODS: Duration of gefitinib treatment was estimated by the time to progression in IDEAL 2, a phase II clinical trial involving patients with advanced or metastatic NSCLC who had previously received platinum-based chemotherapy. Post progression, patients were assumed to receive BSC. Resource utilization was estimated from the clinical trial. The cost of BSC following chemotherapy was provided by CancerCare Manitoba. Costs were expressed in Canadian dollars (2003). RESULTS: Patients (n=102) received gefitinib 250 mg daily. Over 40% of patients achieved a complete response, partial response or stable disease, and clinically significant improvement in disease-related symptoms occurred in most of these patients. Median time to progression was 1.9 months. The median survival time was 7 months. The tolerability profile of gefitinib was mild and there was a low incidence of grade 3/4 adverse reactions. The lifetime cost of treating a patient with gefitinib plus BSC was estimated at $14,496. In sensitivity analyses, that lifetime cost ranged from $13,822 up to $24,915. CONLCUSIONS: The lifetime cost to treat a patient with gefitinib plus BSC was $14,496, which is comparable to costs for other chemotherapies for NSCLC. For example, the lifetime cost of second-line docetaxel was $17,739 (1999 dollars [$19,389 in 2003 dollars]) and for other chemotherapies, lifetime costs ranged from $24,828 up to $41,178 (1995 dollars [$29,059 to $48,196 in 2003 dollars]). 'Iressa' is a trademark of the AstraZeneca group of companies.