 Treatment: Study participants will be given pemetrexed through intravenous infusions. Pemetrexed will be administered once every three weeks. This schedule of pemetrexed once every three weeks will be repeated up to six times. Study participants will also be provided with both folic acid and B12 vitamin supplementation before, during, and after study treatments with pemetrexed. Vitamin supplementation is considered critical and compliance must be followed closely. Several tests and exams will be given throughout the study to monitor patients. Treatments will be discontinued due to disease growth and unacceptable side effects. 