If participants are found to be eligible to take part in this study, they will receive pemetrexed once every 3 weeks through a needle in their vein over about 10 minutes. Every 3 weeks is considered 1 treatment cycle. Once the treatment has started, they will return to the clinic before every treatment cycle. At these visits, they will have a physical exam, a performance status evaluation, and routine blood (about 3-4 teaspoons) and urine tests. They will have a chest x-ray and will be asked to complete a questionnaire about how you are feeling. they will also have a CT or MRI scan after Cycle 1 and every odd cycle from then on.