A Study of Thymidylate Synthase Expression in Patients With Non-Small Cell Lung Cancer

All patients on this study will receive 4 intravenous injections of the chemotherapy drugs pemetrexed and cisplatin (with each injection approximately 3 weeks apart). Patients who complete 4 such injections and respond well to their treatment may continue to receive an injection of chemotherapy drug pemetrexed (approximately every 3 weeks). In general terms, treatment will last until either the patient or the doctor decides that there is no clear benefit in continuing with the treatment. TS levels will be measured from the tumour sample used to make the original diagnosis of NSCLC.