This study will gather and compare data about the effectiveness and safety of two different treatments for extensive Small Cell Lung Cancer (SCLC) in patients who have not received previous chemotherapy. One treatment will use an investigational drug in combination with an FDA approved chemotherapy. The other treatment will use a combination of two FDA approved chemotherapy drugs.

• Drug: topotecan/cisplatin
• Drug: etoposide/cisplatin

Inclusion Criteria:

• Written informed consent (patient's written understanding of and agreement to participate in this study).
• Patients with confirmed extensive small cell lung cancer (SCLC).
• No prior chemotherapy within 5 years of the diagnosis of SCLC.
• Presence of either measurable or non-measurable SCLC by X-ray or physical examination.
• At least 3 weeks since last major surgery (a lesser period is acceptable if decided to be in the best interest of the patient).
• At least 24 hours since prior radiotherapy. Patients who have received radiotherapy must have recovered from any reversible side effects, such as nausea and vomiting.
• Laboratory criteria: Patients must have adequate bone marrow reserve and adequate kidney and liver function.

Exclusion Criteria:

• Symptoms of spreading of the disease to the brain that requires treatment with drugs called steroids.
• Any active infection.
• Severe medical problems other than the diagnosis of SCLC, that would limit the ability of the patient to follow study guidelines or that would expose the patient to extreme risk.
• Ongoing or planned chemotherapy, immunotherapy, radiotherapy, or investigational therapy for the treatment of SCLC.
• Use of an investigational drug within 30 days before the first dose of study medication.
• Women who are pregnant or lactating.
• Patients of child-bearing potential who refuse to practice an adequate form of birth control.
• Patients with clinical evidence of any stomach or intestinal (GI) condition.
• Patients requiring treatment with the drug cyclosporin A.