Inclusion Criteria:

- 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-dose131I 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-dose131I scan within the past 12 weeks:

- Must have 24-hour urine iodine excretion =< 500 mcg within 1 week of 131I scan

- Must be receiving thyroid hormone therapy AND have thyroid-stimulating hormone level
=< 0.5 mU/L

- No known brain metastases

- Performance status:

- ECOG 0-2 OR Karnofsky 60-100%

- Hematopoietic:

- Absolute neutrophil count >= 1,500/mm3;

- Platelet count >= 100,000/mm3;

- WBC >= 3,000/mm3

- 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

- 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

- No prior cytotoxic chemotherapy for thyroid cancer

- 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

- More than 18 months since prior cumulative 131I activity of at least 500 mCi

- More than 12 months since prior amiodarone (Unless 24-hour urinary iodine excretion
is =< 500 mcg)

- No concurrent combination antiretroviral therapy for HIV-positive patients

- No other concurrent anticancer therapy

- No other concurrent investigational agents

- More than 6 months since prior intrathecal iodinated contrast (Unless 24-hour urinary
iodine excretion is =< 500 mcg)

- More than 3 months since prior IV or oral iodinated contrast for radiographic studies
(Unless 24-hour urinary iodine excretion is =< 500 mcg)