Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologic or cytologic diagnosis of non-small cell lung cancer (NSCLC), meeting 1 of
the following staging criteria:

- Stage IIIA disease, meeting all of the following criteria:

- Mediastinal lymph node involvement

- Greater than one mediastinal lymph node enlarged on CT scan, confirmed
by positron emission tomography (PET) scan

- Paralyzed left vocal cord with separate lung primary distinct from the
aorto-pulmonary lymph nodes on the CT scan

- Stage IIIB disease, meeting all of the following criteria:

- N3 lymph node involvement

- Enlarged N3 lymph nodes on CT scan confirmed by PET scan

- Lymph node involvement may not extend to cervical lymph nodes
other than supraclavicular lymph nodes

- Right-sided primary tumor with left vocal cord paralysis

- Evidence of tumor extension into the mediastinum and/or mediastinal
structures by mediastinoscopy, bronchoscopy, or CT scan

- No evidence of malignant pleural effusion unless effusion is only evident
on CT scan

- No more than 1 parenchymal lesions on the same or opposite sides of the
lung

- No brain metastases by CT scan or MRI

PATIENT CHARACTERISTICS:

- SWOG performance status 0 or 1

- Platelet count ≥ 100,000/mm³

- Absolute neutrophil count ≥ 1,500/mm³

- Creatinine ≤ 1.5 times upper limit of normal (ULN)

- Creatinine clearance ≥ 45 mL/min

- Bilirubin normal

- Transaminases (SGOT and/or SGPT) ≤ 1.5 times ULN

- Alkaline phosphatase ≤ 2.5 times ULN

- Total lung volume (i.e., right and left lung minus the gross tumor volume) receiving
greater than 20 Gy of radiation ≤ 40%

- FEV_1 ≥ 70% of predicted

- DLCO ≥ 50 mL/min

- No other concurrent malignancy

- Prior malignancy allowed provided it is in clinical control and is not likely to
impact clinical outcome in the opinion of the treating physician

- No peripheral neuropathy ≥ grade 2

- No serious medical illness, including, but not limited to, any of the following:

- Uncontrolled congestive heart failure

- Uncontrolled angina

- Myocardial infarction

- Cerebrovascular event within the past 6 months

- History of chronic active hepatitis

- History of HIV infection

- Active bacterial infection

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- Must be willing and able to take folic acid, cyanocobalamin (vitamin B12), or
dexamethasone

PRIOR CONCURRENT THERAPY:

- No prior chemotherapy or radiotherapy for NSCLC

- No concurrent participation in another therapeutic investigational study

- Concurrent ibuprofen (400 mg four times daily) allowed during pemetrexed disodium
administration provided the patient has normal renal function

- No concurrent aspirin or other nonsteroidal antiinflammatory drugs (NSAIDs) 2 days
before, during, and for 2 days after pemetrexed disodium administration

- Patients on long-acting NSAIDs (e.g. naproxen sodium, diflunisal, nabumetone, or
celecoxib) must be willing or able to discontinue usage 5 days prior to, during,
and for 2 days after pemetrexed disodium administration