Decitabine in Treating Patients With Metastatic Papillary Thyroid Cancer or Follicular Thyroid Cancer Unresponsive to Iodine I 131

Inclusion Criteria: Histologically confirmed papillary thyroid or follicular thyroid carcinoma: Differentiated disease; Metastatic disease documented by ultrasound, computed tomography (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: Eastern Cooperative Oncology Group (ECOG) 0-2 OR Karnofsky 60-100% Hematopoietic: Absolute neutrophil count >= 1,500/mm3; Platelet count >= 100,000/mm3; White Blood Count (WBC) >= 3,000/mm3 Hepatic: aspartate aminotransferase-alanine aminotransferase (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)