Topotecan in Treating Patients With Recurrent Extensive-Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically confirmed small cell lung cancer (SCLC) Recurrent extensive stage disease No mixed histology Measurable disease At least 1 bidimensionally measurable, non-central nervous system (CNS), indicator lesion confirmed by CT scan or MRI Sensitive disease Responded to prior first-line therapy AND relapsed ≥ 60 days after response (90 days after initiation of first-line therapy) Eligible for high-dose chemotherapy No symptomatic brain metastases affecting performance status PATIENT CHARACTERISTICS: Age 18 and over Performance status Eastern Cooperative Oncology Group (ECOG) 0-2 Life expectancy At least 2 months Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hemoglobin ≥ 9.0 g/dL Hematocrit > 35% (without transfusion) Hepatic Serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) ≤ 2 times normal* Alkaline phosphatase ≤ 2 times normal* Bilirubin ≤ 2.0 mg/dL Albumin > 2.5 g/dL Hepatitis B surface antigen negative No significant hepatic disease Note: *≤ 5 times upper limit of normal if liver metastases are present Renal Creatinine clearance ≥ 40 mL/min Cardiovascular No history of cardiac arrhythmias No congestive heart failure No ischemic heart disease No stroke or other embolic disease requiring daily treatment that would preclude study participation Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after study participation HIV negative No known seizure disorder No active infection requiring systemic therapy within the past 2 weeks No known hypersensitivity to topotecan hydrochloride No medical or psychiatric condition that would preclude study participation No other malignancy except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or stage A low-grade prostate cancer PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy See Disease Characteristics More than 4 weeks since prior antineoplastic and/or myelosuppressive chemotherapy No more than 1 prior chemotherapy regimen (except for adjuvant chemotherapy) for SCLC No prior topotecan hydrochloride Endocrine therapy Not specified Radiotherapy Not specified Surgery Not specified Other More than 2 months since prior investigational agent No other concurrent investigational agent