Busulfan and Fludarabine Before Donor Stem Cell Transplant in Treating Patients With Hematologic Cancer

DISEASE CHARACTERISTICS:

* Diagnosis of 1 of the following hematopoietic disorders:

  * Chronic myelogenous leukemia (CML), meeting 1 of the following criteria:

    * Chronic phase disease failing imatinib mesylate therapy

      * Progressive disease OR failed to achieve a major cytogenetic response at 1 year after initiation of therapy
    * Accelerated phase disease, meeting 1 of the following criteria:

      * Failed to achieve complete cytogenetic remission at 1 year after initiation of therapy
      * Failed to achieve any cytogenetic response at 3 or 6 months during therapy
      * Progressive disease, demonstrated by worsening cytogenetic response in 2 consecutive analyses separated by 4 weeks
    * Blast crisis with \< 10% blasts in bone marrow within 6 weeks of transplantation
  * Acute myeloid leukemia (AML), meeting 1 of the following criteria:

    * In second or greater remission
    * In first remission with poor prognosis cytogenetics \[-5, -5q, -7, -7q and ≥ 2 cytogenetic abnormalities, t(6,9), t(9,11), or Philadelphia chromosome\]
    * In hematologic remission but with persistent cytogenetic abnormalities
    * Primary refractory AML with \< 10% blasts in bone marrow within 6 weeks of transplantation
  * Myelodysplasia with \< 20% blasts in bone marrow within 6 weeks of transplantation and meeting 1 of the following criteria:

    * Advanced disease (International Prognostic Scoring System \[IPSS\] score intermediate-1, intermediate-2, or high risk)
    * Myelodysplastic syndromes (MDS) with progression to AML
    * Treatment-related AML
  * Acute lymphocytic leukemia (ALL), meeting 1 of the following criteria:

    * In second or greater remission
    * In first remission with high-risk cytogenetics \[Philadelphia chromosome; t(4,11); and -7\]
    * Primary refractory ALL with \< 10% blasts in the bone marrow
  * Severe aplastic anemia that has failed immunosuppressive therapy
  * Non-Hodgkin's lymphoma, meeting 1 of the following criteria:

    * In second or greater remission
    * Relapsed disease in a patient not eligible for autologous stem cell transplantation
  * Lymphoproliferative disease (e.g., chronic lymphocytic leukemia or Waldenstrom's macroglobulinemia), meeting 1 of the following criteria:

    * In second or greater remission
    * Relapsed disease in a patient not eligible for autologous stem cell transplantation
  * Multiple myeloma, meeting 1 of the following criteria:

    * Stage II or III disease in first or greater relapse
    * Refractory disease
    * Newly diagnosed disease with chromosome 13 abnormalities
  * Advanced myeloproliferative disease, meeting 1 of the following criteria:

    * Myelofibrosis requiring \> 2 units of packed red blood cells each month
    * Essential thrombocythemia or polycythemia rubra vera that has progressed to AML
    * Failed prior AML therapy
* No active, uncontrolled CNS leukemia
* Not eligible for autologous or mini-allogeneic transplantation
* No fully matched or single-antigen mismatched sibling donor available
* HLA-matched unrelated donor available

  * HLA typed at HLA-A, -B, -C, -DRB1 and/or -DQB1 by high-resolution techniques
  * For patients without HLA identical donors, mismatches at DQ (i.e., 8/8 match) and 1 additional mismatch at the allele level at HLA-A, -B, -C, or -DRB1 (i.e., 7/8 molecular match) allowed

PATIENT CHARACTERISTICS:

* ECOG performance status 0-2
* Creatinine \< 2.0 mg/dL
* Pulmonary diffusing capacity \> 40% of predicted
* Cardiac ejection fraction \> 40% by MUGA or echocardiography
* No active liver disease
* Bilirubin ≤ 2.0 mg/dL
* Alkaline phosphatase \< 3 times upper limit of normal (ULN)
* AST \< 3 times ULN
* Hepatitis C or active hepatitis B (HBV) allowed provided a liver biopsy is performed and ≤ grade 2 inflammation is present

  * Patients with active HBV viral replication must receive antiviral therapy
* HIV negative
* No ongoing active infection
* Not pregnant or nursing
* Negative pregnancy test

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* More than 3 weeks since prior chemotherapy except for hydroxyurea or imatinib mesylate
* More than 3 months since prior interferon