All patients will also receive folic acid 350-1000 mcg. po once daily beginning approximately 1 week prior to the first dose of pemetrexed and continuing until completion of pemetrexed, Vitamin B12 1000 mcg. IM every 9 weeks beginning approximately 1 week prior to the first dose of pemetrexed and continuing until completion of pemetrexed, and dexamethasone 4 mg po bid the day before, the day of, and the day following each treatment with pemetrexed