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