Inclusion Criteria:

• Patients will be clinically staged using AJCC/UICC TNM staging criteria. Eligible stages:

  1. Patients must be M0
  2. Patients with T1, T2, and T3 disease (without cardiac involvement) are eligible (T status can be established clinically and radiologically or at exploratory thoracotomy without surgical resection
  3. Patients with N0, N1,or N2 disease are eligible
• Performance status of 0 to 1 on the ECOG performance status schedule.
• No prior systemic chemotherapy and no prior intracavitary cytotoxic drugs or immunomodulators, unless given for the purpose of chemical pleurodesis
• No previous radiation therapy
• Estimated life expectancy of at least 12 weeks

Exclusion Criteria:

Patients will be excluded if they meet ANY of the following criteria:

• Have received treatment within the last 30 days with a drug that has not received regulatory approval for any indication at the time of study entry
• Have previously completed or withdrawn from this study or any other study investigating pemetrexed
• Pregnancy or breast-feeding
• Serious concomitant systemic disorders (i.e. active infection) that, in the opinion of the investigator, would compromise the safety of the patient or compromise the patient's ability to complete the study
• Second active primary malignancy (except in situ carcinoma of the cervix, adequately treated non-melanomatous carcinoma of the skin, low grade (Gleason score less than or equal to 6), localized adenocarcinoma of the prostate or other malignancy treated at least 2 years previously with no evidence of recurrence