<qa>  What is the name of the study that participants will take ZD1839 by mouth daily?In this study, participants will take ZD1839 by mouth daily. Once the treatment has started, participants will return to the clinic before every treatment cycle every 4 weeks for the first 4 months then every 8 weeks thereafter. At these visits, participants will have a physical exam and blood tests will be performed. About 2-4 teaspoons of blood will be drawn at each visit. The doctor will also check on how participants are tolerating ZD1839 side effects. Every 8 weeks, participants will have their tumor evaluated by radiographic scans. This may include either a CT or MRI and a chest X-ray. 