Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed thyroid cancer

- Metastatic or locally advanced disease

- Not amenable to OR unresponsive or refractory to local therapy and/or
radioactive iodine, depending on cell type

- Medullary and anaplastic thyroid carcinomas are considered unresponsive on
the basis of histology alone

- Well-differentiated papillary or follicular thyroid carcinomas are
considered refractory if there is no evidence of uptake on radioactive
iodine scanning OR the tumor progresses despite treatment with radioactive
iodine

- Measurable disease

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-2

Life expectancy

- Not specified

Hematopoietic

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

- Platelet count ≥ 75,000/mm^3

Hepatic

- AST or ALT ≤ 3 times normal

- Bilirubin ≤ 1.5 times normal

- No unstable or uncompensated hepatic disease

Renal

- Creatinine ≤ Common Toxicity Criteria grade 2

- No unstable or uncompensated renal disease

Cardiovascular

- No unstable or uncompensated cardiac disease

Pulmonary

- No clinically active interstitial lung disease

- Chronic, stable, asymptomatic radiographic changes allowed

- No unstable or uncompensated respiratory disease

Other

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

- No other severe or uncontrolled systemic disease

- No other significant clinical disorder or laboratory finding that would preclude
study participation

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- No concurrent chemotherapy

Endocrine therapy

- Not specified

Radiotherapy

- See Disease Characteristics

- No concurrent local-regional radiotherapy to a primary disease site

- No concurrent radiotherapy to a bony or CNS metastasis

Surgery

- Completely healed after prior oncologic or other major surgery

Other

- Recovered from all prior anticancer therapy

- More than 30 days since prior non-approved or investigational drugs

- No concurrent use of any of the following agents:

- Phenytoin

- Carbamazepine

- Barbiturates

- Rifampin

- Phenobarbital

- Hypericum perforatum (St. John's wort)

- Systemic retinoids

- Cyclosporine

- Verapamil

- Diltiazem

- Nicardipine

- Nifedipine

- Nitrendipine

- Erythromycin

- Theophylline

- Ketoconazole

- Itraconazole

- Antihistamines (e.g., terfenadine or astemizole)

- No concurrent grapefruit or grapefruit juice

- No other concurrent systemic anticancer treatment