Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed bronchoalveolar carcinoma (BAC) or BAC variants such as
adenocarcinoma with BAC features or BAC with invasive adenocarcinoma

- Cytology specimens, such as bronchial brushings, washings, or fine needle
aspiration specimens alone are not acceptable for diagnosis

- Stage IV disease OR selected stage IIIB (T4 [secondary to malignant pleural effusion
only], any N, M0) disease

- Incompletely resected or unresectable disease

- Pleural effusions, ascites, or laboratory parameters cannot be only evidence of
disease

- Measurable disease or nonmeasurable disease documented by CT scan

- No known brain metastases

PATIENT CHARACTERISTICS:

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

- SGOT and SGPT ≤ 2.5 times ULN ( ≤ 5 times ULN if due to liver metastases)

- Alkaline phosphatase ≤ 2.5 times ULN ( ≤ 5 times ULN if due to bone metastases)

- Creatinine clearance ≥ 45 mL/min OR creatinine ≤ 1.5 times ULN

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 75,000/mm³

- Zubrod 0-2

- No history of allergic reaction to compounds of similar chemical or biological
composition as pemetrexed disodium

- Must provide smoking history

- No other malignancy within the past 5 years except adequately treated basal cell or
squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated
stage I or II cancer in complete remission

- Not pregnant or nursing

- Fertile patients must use effective contraception

- Able to swallow pills

PRIOR CONCURRENT THERAPY:

- No more than 2 prior systemic therapies (including epidermal growth factor receptor
inhibitor)

- At least 28 days since prior systemic therapy

- Patients treated with prior erlotinib or gefitinib must have shown progression since
treatment

- No prior pemetrexed disodium

- At least 28 days since prior radiotherapy and recovered

- Must have measurable or nonmeasurable disease outside previously irradiated area
or a new lesion within previously irradiated area

- At least 14 days since prior palliative radiotherapy and recovered

- At least 28 days since prior thoracic or major surgery and recovered

- No concurrent surgery

- No other concurrent therapy (hormonal, biologic or radiotherapy) for this disease

- No concurrent antiretroviral therapy

- Patients should discontinue non-steroidal anti-inflammatory drugs (NSAIDs) with
longer half lives (etodolac, ketordac, sulindac, naproxen, naproxen sodium,
oxaprozin, nabumetone, diflunisal, salsalate, celecoxib, rofecoxib, valdecoxib,
meloxicam, piroxicam) at least 5 days before and for 2 days following pemetrexed
treatment