PRIMARY OBJECTIVES:~I. Determine the response rate, time to progression, and overall survival of patients with recurrent small cell lung cancer treated with imatinib mesylate.~II. Correlate the presence of c-Kit mutations in tumor tissue with treatment response in patients treated with this drug.~III. Correlate individual patient variation in clinical (toxicity and/or activity), pharmacologic (pharmacokinetic/pharmacodynamic parameters), and/or biologic (correlative laboratory study results) responses to this drug with genetic differences in proteins involved in drug response (transport, metabolism, and/or mechanism of action).~OUTLINE: This is a multicenter study. Patients are stratified according to length of prior therapy (less than 3 months vs at least 3 months).~Patients receive oral imatinib mesylate twice daily for 28 days. Courses continue in the absence of disease progression or unacceptable toxicity.~*Patients are followed every 3 months until disease progression and then every 6 months for up to 3 years after registration.~NOTE: *Patients who develop CNS metastasis as the only site of disease progression receive therapeutic whole-brain radiotherapy and then resume study therapy.~PROJECTED ACCRUAL: A total of 41 patients for stratum I will be accrued within 21 months and 50 patients for stratum II will be accrued within 25 months for this study.
Phase II trial to study the effectiveness of imatinib mesylate in treating patients who have recurrent small cell lung cancer. Imatinib mesylate may stop the growth of cancer cells by blocking the enzymes necessary for cancer cell growth.