Clofarabine or Daunorubicin Hydrochloride and Cytarabine Followed By Decitabine or Observation in Treating Older Patients With Newly Diagnosed Acute Myeloid Leukemia

Inclusion Criteria for Step 1 (Induction): * Sexually active males must be strongly advised to use an accepted and effective method of contraception * Aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin =\< grade 1 * Newly-diagnosed AML patients according to World Health Organization (WHO) classification who are considered candidates for intensive chemotherapy based upon examination of peripheral blood or bone marrow aspirate specimens or touch preparations of the bone marrow biopsy obtained within two weeks prior to randomization; a bone marrow aspirate is required for enrollment; however, on occasion there is discordance between percentage of myeloblasts on the differential of the peripheral blood or aspirate; the peripheral blood criteria are sufficient for diagnosis; confirmatory immunophenotyping will be performed centrally * ECOG performance status (PS) 0-3 (restricted to ECOG PS 0-2 if \>= 70 years of age) * Patients with secondary AML are eligible for enrollment onto the trial; secondary AML is defined as AML that has developed in a person with a history of antecedent blood count abnormalities, or myelodysplastic syndrome (MDS), or a myeloproliferative disorder (excluding chronic myeloid leukemia); or a history of prior chemotherapy or radiation therapy for a disease other than AML * Total serum bilirubin =\< 1.5 times upper limit of normal (ULN) (=\< grade 1); if total bilirubin is 2 to 3 mg/dL, but direct bilirubin is normal, then the …