Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed non-small cell lung cancer (NSCLC)

- Progression of disease during platinum-based (cisplatin or carboplatin) chemotherapy
or within 3 months of completing chemotherapy

- Treatment with other agents since prior platinum-based chemotherapy allowed

- Measurable disease

- Target lesions within a prior radiation field must have documented evidence of
progression at least 8 weeks after the completion of radiotherapy

- No active brain or leptomeningeal metastases

- Treated brain metastases allowed at least 4 weeks after the completion of
appropriate therapy

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-2

Life expectancy

- Not specified

Hematopoietic

- Absolute neutrophil count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

- Hemoglobin at least 8 g/dL

Hepatic

- Bilirubin no greater than upper limit of normal (ULN)

- AST/ALT no greater than 2.5 times ULN (if alkaline phosphatase is no greater than
ULN)

- Alkaline phosphatase no greater than 5 times ULN (if AST and ALT are greater than
ULN)

- No history of chronic hepatitis

Renal

- Creatinine no greater than 1.5 times ULN

Cardiovascular

- No active thromboembolic event within the past 4 weeks

- No uncontrolled congestive heart failure

- No uncontrolled angina

- No myocardial infarction and/or stroke within the past 6 months

Pulmonary

- No evidence of clinically active interstitial lung disease

Gastrointestinal

- No history of gastrointestinal bleeding within the past 6 months

- No history of peptic ulcer disease

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- Must weigh at least 110 pounds (50 kg)

- HIV negative

- No allergy to sulfonamides

- No allergy to any NSAID, including celecoxib

- No known severe hypersensitivity to gefitinib or any of its excipients

- No other malignancy within the past 3 years except adequately treated basal cell or
squamous cell skin cancer or carcinoma in situ of the cervix

- No history of dementia, active psychiatric disorder, or any other condition that
would preclude study compliance

- No other concurrent serious medical condition

PRIOR CONCURRENT THERAPY:

Biologic therapy

- No prior epidermal growth factor receptor inhibitor

- No concurrent biologic therapy

Chemotherapy

- See Disease Characteristics

- More than 2 weeks since prior chemotherapy

Endocrine therapy

- Not specified

Radiotherapy

- Recovered from prior radiotherapy

Surgery

- Recovered from prior surgery

Other

- Recovered from prior therapy

- More than 2 weeks since prior investigational therapy

- More than 1 week since prior fluconazole

- More than 30 days since prior participation in another investigational agent clinical
trial

- More than 30 days since prior chronic nonsteroidal anti-inflammatory drugs (NSAIDs),
including celecoxib or rofecoxib

- No prior gefitinib

- No prior cyclooxygenase-2 (COX-2) inhibitor or another clinical trial for NSCLC

- No other concurrent NSAIDs

- Concurrent aspirin allowed (not to exceed 325 mg/day)

- No other concurrent COX-2 inhibitors

- No concurrent lithium

- No concurrent fluconazole

- No concurrent use of any of the following:

- Phenytoin

- Carbamazepine

- Barbiturates

- Rifampin

- Phenobarbital

- Hypericum perforatum