Cisplatin + Etoposide +/- Concurrent ZD6474 in Previously Untreated Extensive Stage Small Cell Lung Cancer

OUTLINE: This is a multi-center study. Arm A: Cisplatin 60mg/m2 Day 1 + Etoposide 120mg/m2 Day 1,2,3 + Placebo oral daily given continuously for the duration of the study Arm B: Cisplatin 60mg/m2 Day 1 + Etoposide 120mg/m2 Day 1,2,3 + ZD6474 100mg oral daily given continuously for the duration of the study For both arms, PE and toxicity evaluation prior to each cycle and disease assessment by imaging every 2 cycles. Patients with non-PD and acceptable toxicity will continue protocol therapy; patients with progressive disease or excessive toxicity will be taken off treatment. Cycles will be repeated every 21 days up to a total of 4 cycles. ECOG Performance Status of 0 or 1 Life Expectancy: Not specified Hematopoietic: * Platelets \> 100K/mm3 * Absolute neutrophil count (ANC) \> 1.5K/mm3 Hepatic: * Bilirubin \< 1.5 x ULN * Aspartate aminotransferase (AST) \< 2.5 x ULN or \< 5 x ULN if judged by the investigator to be related to liver metastases * Alkaline phosphatase \< 2.5 x ULN or \< 5 x ULN if judged by the investigator to be related to liver metastases Renal: * Serum creatinine \< 1.5 x ULN or Calculated creatinine clearance of \> 45 cc/min using the Cockcroft-Gault formula Cardiovascular: * No clinically significant cardiac event such as myocardial infarction; New York Heart Association (NYHA) classification of heart disease \>2 (see SPM) within 3 months prior to registration for protocol therapy * No presence of cardiac disease that, in the opinion of the Investigator, increases the risk of ventricular arrhythmia. * No history of arrhythmia (multifocal premature ventricular contractions (PVCs), bigeminy, trigeminy, ventricular tachycardia, or uncontrolled atrial fibrillation) which is symptomatic or requires treatment (CTCAE grade 3) or asymptomatic sustained ventricular tachycardia. Atrial fibrillation, controlled on medication is permitted.