Liposomal SN-38 in Treating Patients With Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed small cell lung cancer meeting 1 of the following criteria: * Previously untreated disease * Extensive stage disease, as defined by any of the following: * Metastatic disease outside of the chest * Contralateral supraclavicular or contralateral hilar nodes that cannot be included in a single radiation port * Malignant pleural effusion * Previously treated disease * Limited or extensive stage disease * Measurable disease * Lesions ≥ 1 cm and \< 2 cm must be measured by spiral CT scan for pre- and post-treatment tumor assessment * UGT1A1\*28 genotype wt/wt (6/6 promoter TA repeats) OR wt/\*28 (6/7 promoter TA repeats) * No \*28/\*28 (7/7 promoter TA repeats) genotype * No mixed histology * No uncontrolled CNS metastasis * Previously treated, stable CNS metastasis allowed * No superior vena cava syndrome * No malignant pericardial effusion * No near obstruction of the trachea or main stem bronchi PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 Hepatic * Total bilirubin \< 1.5 times upper limit of normal (ULN) OR * Direct bilirubin normal Renal * Creatinine \< 1.5 times ULN Cardiovascular * No unstable angina pectoris * No uncontrolled congestive heart failure * No myocardial infarction within the past 3 months Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 6 months after study participation * No syndrome of inappropriate antidiuretic hormone secretion * No ectopic adrenocorticotrophic syndrome * No Lambert-Eaton myasthenic syndrome * No other severe paraneoplastic syndrome * No active infection requiring oral or parenteral antibiotics * No other life threatening disease * No other malignancy except basal cell or squamous cell skin cancer, localized prostate cancer, superficial bladder cancer, or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy * No concurrent filgrastim (G-CSF) during course 1 of study treatment Chemotherapy * No more than 1 prior chemotherapy regimen for this malignancy * Prior cyclophosphamide, doxorubicin, and vincristine (CAV) alternating with etoposide and cisplatin (EP) allowed * More than 21 days since prior chemotherapy Endocrine therapy * Not specified Radiotherapy * More than 14 days since prior radiotherapy * Concurrent palliative radiotherapy allowed except radiotherapy to a solitary measured index lesion Surgery * More than 21 days since prior major surgery Other * No other concurrent treatment for this malignancy * No other concurrent investigational treatment