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