DISEASE CHARACTERISTICS:

• Histologically confirmed papillary thyroid or follicular thyroid carcinoma

  • Differentiated disease

  • Metastatic disease documented by ultrasound, CT scan (without iodinated contrast), or MRI

    • All metastatic disease foci ≤ 10 mm in all dimensions
• Must have been treated with total or near-total thyroidectomy AND at least 1 course of iodine I 131 (^131I) (≥29.9 mCi) OR demonstrated negative uptake on a postoperative low-dose^131I scan

• Must have undergone whole body ^131I scan* 1-3 days after administration of ≤ 5.5 mCi of ^131I demonstrating no visible iodine uptake within the lesions unless demonstrated negative uptake on a postoperative low-dose^131I scan within the past 12 weeks

  • Must have 24-hour urine iodine excretion ≤ 500 mcg within 1 week of ^131I scan NOTE: *Scanning must have been performed after a two-dose regimen of thyrotropin alfa
• Must be receiving thyroid hormone therapy AND have thyroid-stimulating hormone level ≤ 0.5 mU/L
• No known brain metastases

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2 OR
• Karnofsky 60-100%

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• WBC ≥ 3,000/mm^3

Hepatic

• AST and ALT ≤ 2.5 times upper limit of normal
• Bilirubin normal

Renal

• Creatinine not elevated OR
• Creatinine clearance ≥ 60 mL/min

Cardiovascular

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No prior allergic reaction attributed to compounds of similar chemical or biological composition to decitabine
• No concurrent uncontrolled illness
• No active or ongoing infection
• No psychiatric illness or social situation that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No prior cytotoxic chemotherapy for thyroid cancer

Endocrine therapy

• See Disease Characteristics

Radiotherapy

• See Disease Characteristics
• At least 6 months since prior external beam radiotherapy administered for locoregional disease in the thyroid bed or to the cervical or upper mediastinal lymph node regions (no more than 6,000 cGy)
• More than 6 months since other prior radiotherapy and recovered
• More than 6 months since prior therapeutic ^131I > 10 mCi OR
• More than 18 months since prior cumulative ^131I activity of at least 500 mCi
• More than 3 months since prior IV or oral iodinated contrast for radiographic studies*
• More than 6 months since prior intrathecal iodinated contrast* NOTE: *Unless 24-hour urinary iodine excretion is ≤ 500 mcg

Surgery

• See Disease Characteristics

Other

• More than 12 months since prior amiodarone*
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent anticancer therapy
• No other concurrent investigational agents NOTE: *Unless 24-hour urinary iodine excretion is ≤ 500 mcg