Captopril in Treating Patients With Non-Small Cell Lung Cancer or Limited-Stage Small Cell Lung Cancer That Has Been Previously Treated With Radiation Therapy With or Without Chemotherapy

DISEASE CHARACTERISTICS: * One of the following histologically or cytologically confirmed diagnoses: * Stage II-IIIB non-small cell lung cancer (NSCLC) * Stage I central NSCLC * No peripheral coin lesions * Limited stage small cell lung cancer * Nonmetastatic disease that is receiving radiotherapy and the target is confined to a single radiotherapy treatment area * Planning to receive radiotherapy * At least 45 Gy to be delivered to the target volume * More than 25% of total lung volume to receive \> 20 Gy if receiving radiotherapy alone PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Zubrod 0-1 Hematopoietic * Absolute granulocyte count greater than 1,000/mm\^3 * Platelet count greater than 75,000/mm\^3 * Hemoglobin greater than 9.0 g/dL (transfusion allowed) Hepatic * Bilirubin less than 1.5 mg/dL * Serum glutamate oxaloacetate transaminase (SGOT) less than 2 times normal Renal * Blood urea nitrogen (BUN) less than 25 mg/dL * Creatinine less than 1.6 mg/dL * Urine protein less than 10 mg/dL * Urine glucose negative Cardiovascular * Systolic blood pressure greater than 110 mm Hg * Diastolic blood pressure greater than 60 mm Hg Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Sodium normal * Potassium normal * No collagen vascular disease (e.g., lupus or scleroderma) * Rheumatoid arthritis allowed * No known hypersensitivity to ACE inhibitors PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * Induction or concurrent chemotherapy allowed either during radiotherapy or during therapy with captopril * No concurrent methotrexate Endocrine therapy * Not specified Radiotherapy * See Disease Characteristics Surgery * Prior pulmonary lobectomy or segmentectomy allowed * No prior pneumonectomy Other * No concurrent angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor antagonists for hypertension or congestive heart failure * No concurrent lithium * No concurrent procainamide