Reduced Intensity Chemotherapy and Radiation Therapy Before Donor Stem Cell Transplant in Treating Patients With Hematologic Malignancies

Inclusion Criteria: * Patients treated on this study will have: * Acute myeloid leukemia in morphologic complete remission (CR) not requiring treatment for their disease for 4 weeks * A history of acute myeloid leukemia (AML) with \< 10% residual blasts (use highest count on staging studies) after induction therapy and persisting with \< 10% blasts for at least 8 weeks without reinduction and at the time of HSCT * Refractory anemia (RA) or refractory anemia with ring sideroblasts (RARS) or isolated 5q- * Refractory anemia with excess blasts (RAEB)-1, refractory cytopenia with multilineage dysplasia (RCMD)+/-ringed sideroblasts (RS), or myelodysplastic syndrome (MDS) not otherwise specified (NOS) with stable disease for at least 3 months * RAEB-2 must demonstrate chemo-responsiveness; chemo-responsiveness is defined as a persistent blast percentage decrease by at least 5 percentage points to therapy and there must be =\< 10% blasts (use highest count on staging studies) after treatment and at the time of transplant * Hodgkin or Indolent non-Hodgkin's lymphoma * Myeloma with \< 5% plasma cells in the marrow * Myeloproliferative disorders (excludes chronic myelomonocytic leukemia \[CMML\]) * Aplastic anemia * A hematological or oncological disease (not listed) in which allogeneic HSCT is thought to be beneficial, and the disease is chemoresponsive * Patients without clear manifestation of their disease status in terms of stage and/or responsiveness should…