Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of extensive-stage small cell lung cancer

- No untreated brain metastases

- No active symptoms related to brain metastases

PATIENT CHARACTERISTICS:

- ECOG performance status 0-2

- Hemoglobin ≥ 9.0 g/dL

- ANC ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Total bilirubin ≤ 1.5 times upper limit of normal (ULN)

- ALT and AST ≤ 2.5 times ULN (≤ 5 times ULN for patients with liver involvement)

- Creatinine ≤ 1.5 times ULN

- INR < 1.5 or PT/PTT normal

- No history of cardiac disease, including any of the following:

- NYHA class III-IV congestive heart failure

- Unstable angina (i.e., anginal symptoms at rest)

- Onset of angina within the past 3 months

- Myocardial infarction within the past 6 months

- No cardiac ventricular arrhythmias requiring anti-arrhythmic therapy

- No uncontrolled hypertension, defined as systolic blood pressure (BP) > 150 mm Hg or
diastolic BP > 90 mm Hg, despite optimal medical management

- No thrombolic or embolic events, such as cerebrovascular accident or transient
ischemic attacks, within the past 6 months

- No pulmonary hemorrhage/bleeding event ≥ CTCAE grade 2 within the past 4 weeks

- No other hemorrhage/bleeding event ≥ CTCAE grade 3 within the past 4 weeks

- No known HIV infection or chronic hepatitis B or C infection

- No active clinically serious infection > CTCAE grade 2

- No serious non-healing wound, ulcer, or bone fracture

- No evidence or history of bleeding diathesis or coagulopathy

- No significant traumatic injury within the past 4 weeks

- No known or suspected allergy to sorafenib tosylate or to any other drug given during
the study

- No condition that would impair the patient's ability to swallow whole pills

- No known malabsorption problem

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective barrier contraception

- Male patients must use effective contraception during and for ≥ 3 months after
completion of sorafenib tosylate

PRIOR CONCURRENT THERAPY:

- Prior radiotherapy to the brain allowed

- No prior chemotherapy

- More than 4 weeks since prior major surgery or open biopsy

- No concurrent Hypericum perforatum (St. John's wort) or rifampin

- Concurrent anti-coagulation treatment, such as warfarin or heparin, allowed