A Comparison of Two Doses of Pemetrexed in Patients Who Have Lung Cancer

Inclusion Criteria: * Diagnosis of locally advanced or metastatic (Stage III or IV at entry) non-small cell lung cancer (NSCLC) that is not amenable to curative therapy. * Patients must have been previously treated with one platinum-containing chemotherapy regimen for locally advanced or metastatic disease. Patients are also eligible if they have received one platinum-based chemotherapy regimen as neoadjuvant or adjuvant chemotherapy, but must have received an additional chemotherapy regimen upon recurrence. * No more than two prior systemic anti-cancer therapies will be allowed. * Prior radiation therapy is allowed to less than 25% of the bone marrow. Prior radiation to the whole pelvis is not allowed. Prior radiotherapy must be completed at least 2 weeks before study enrollment, and the patient must have recovered from the acute toxic effects of the treatment prior to study enrollment. Exclusion Criteria: * Pregnancy. * Breast-feeding. * Second primary malignancy that is clinically detectable at the time of consideration for study enrollment. * Inability to interrupt aspirin, or other nonsteroidal anti-inflammatory agents for a 5-day period. * Inability or unwillingness to take folic acid or vitamin B12 supplementation.