The purpose of this study is to find better treatment for lung cancer and to find out what effects the combined treatment of carboplatin and gemcitabine when given with or without dexamethasone have on cancer.

This study will determine if dexamethasone, when given before standard chemotherapy will increase the cancer fighting effects and reduce the side effects of chemotherapy.

Subjects enrolled in the study will be placed in one of two treatment arms. All subjects have a 50-50 chance of being placed into either treatment arm. Treatment Arm 1 will receive chemotherapy alone, Treatment Arm 2 will receive chemotherapy with dexamethasone given pre-treatment.

Inclusion Criteria:

• Untreated, stage IIIB with pleural effusion
• Untreated, Stage IV, non-small cell lung cancer
• Recurrent after surgery if no previous radiation therapy or chemotherapy were administered as part of their primary treatment, except for palliative radiotherapy
• 18 years of age or older
• ECOG PS 0, 1 or 2
• At Least one target lesion according to the RECIST Criteria
• Adequate organ and marrow function

Exclusion Criteria:

• Previous cancer history unless they have had curative treatment completed at least 5 years prior to entry.
• No previous radiotherapy, chemotherapy or immunotherapy for NSCLC, except for radiation therapy to the brain to control metastasis, bone to control pain, or lung to relieve bronchial obstruction.
• No radiation therapy for any previous cancer to more than 25% of bone marrow.
• Uncontrolled, intercurrent illness
• Non-study corticosteroids
• Pregnant women
• Peripheral neuropathy greater than grade 1
• Uncontrolled seizures, central nervous system disorders
• Major surgery within 4 weeks of the start of study treatment
• Lack of complete recovery from major surgery.
• Glaucoma
• Lack of physical integrity of upper gastrointestinal tract, inability to swallow tablets
• Severe acquired or hereditary immunodeficiency
• Patients with brain metastases must receive definitive treatment (radiation, surgery or both) and be clinically and radiologically stable for 4 weeks & off corticosteroids for at least 2 weeks prior to randomization.