Reduced-Intensity Busulfan and Fludarabine With or Without Antithymocyte Globulin Followed by Donor Stem Cell Transplant in Treating Patients With Hematologic Cancer or Other Disease

DISEASE CHARACTERISTICS:

* Histologically confirmed diagnosis of 1 of the following:

  * Chronic lymphocytic leukemia (CLL), meeting the following criteria:

    * Absolute lymphocyte count \> 5,000/mm³
    * Lymphocytes must appear morphologically mature with \< 55% prolymphocytes
    * Lymphocyte phenotype with expression of CD19 and cluster of differentiation 5 (CD5)
  * Prolymphocytic leukemia (PLL), meeting the following criteria:

    * Absolute lymphocyte count \> 5,000/mm³
    * More than 55% prolymphocytes
    * Morphologically diagnosed
  * Chronic myelogenous leukemia (CML), meeting the following criteria:

    * Diagnosis of CML or similar myeloproliferative disorders based on t(9;22) or related t(9;12) cytogenetic abnormalities AND characterized by elevated white blood cell (WBC) counts in peripheral blood or bone marrow
    * In first chronic phase CML and a candidate for treatment with reduced-dose busulfan
    * Patients with other cytogenetic abnormalities, such as t(9;12), that are associated with an aggressive clinical course are eligible
  * Non-Hodgkin's lymphoma (NHL), meeting the following criteria:

    * Any World Health Organization (WHO) class histologic subtype allowed
    * Core biopsies are acceptable provided they contain adequate tissue for primary diagnosis and immunophenotyping
    * Bone marrow biopsies as sole means of diagnosis are not allowed for follicular lymphoma
  * Hodgkin's lymphoma, meeting the following criteria:

    * Any WHO class histologic subtype allowed
    * Core biopsies are acceptable provided they contain adequate tissue for primary diagnosis and immunophenotyping
  * Multiple myeloma, meeting the following criteria:

    * Active disease requiring treatment (Durie-Salmon stages I, II, or III)
  * Acute myeloid leukemia with documented control, defined as \< 10% bone marrow blasts and no circulating blasts
  * Acute lymphoblastic leukemia, meeting the following criteria:

    * In early first relapse or beyond OR in first complete remission and has 1 of the following high-risk features:

      * t(9;22) or t(4;11)
      * WBC count \> 30,000/mm³ at presentation
      * Non-T-cell phenotype
      * More than 30 years of age
  * Agnogenic myeloid metaplasia/myelofibrosis

    * Patients who are transfusion dependent or who have evolving myelodysplastic or leukemic features or high-risk cytogenetic abnormalities are eligible
  * Myelodysplastic syndromes (MDS) as defined by WHO criteria
* Meets 1 of the following criteria:

  * Over 55 years of age
  * Ineligible for busulfan-based therapy based on diminished organ function or poor performance status
  * Indolent and chemotherapy-responsive CLL, low-grade NHL, small lymphocytic lymphoma, or PLL
* Patients who have undergone prior autologous stem cell transplantation are preferentially enrolled on clinical trial CALGB-100002, if available and patient is eligible
* HLA-matched or mismatched related donor or HLA-matched unrelated donor available

  * HLA-identical sibling (6/6 or 9/10) (minimal serologic typing required for class I \[A, B\]; molecular typing required for class II (DRB1))
  * 9/10 matched unrelated donor (MUD) (molecular analysis at HLA A, B, C, DRB1, and DQB1 by high resolution typing required)
  * 5/6 MUD (molecular analysis at HLA A, B, and DRB1 required)
  * No syngeneic donors

PATIENT CHARACTERISTICS:

* Creatinine clearance ≥ 40 mL/min
* Bilirubin ≤ 3 times upper limit of normal (ULN)
* aspartate aminotransferase (AST) ≤ 3 times ULN
* Diffusing capacity of the lungs for carbon monoxide (DLCO) \> 40% with no symptomatic pulmonary disease
* Left ventricular ejection fraction (LVEF) ≥ 30% by multigated acquisition scan (MUGA)
* No uncontrolled diabetes mellitus or active serious infection
* No known hypersensitivity to Escherichia coli-derived products
* No HIV infection
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* More than 4 weeks since prior chemotherapy, radiotherapy (except prophylactic cranial x-ray therapy), or surgery