Fludarabine and Radiation Therapy in Treating Patients Who Are Undergoing Donor Stem Cell Transplant for Chronic Phase or Accelerated Phase Chronic Myelogenous Leukemia

DISEASE CHARACTERISTICS: Diagnosis of Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia, meeting 1 of the following criteria: Chronic phase Ph+ by cytogenetics or fluorescent in situ hybridization (FISH) assay Accelerated phase, meeting any of the following criteria: More than 10% but < 30% myeloblasts and promyelocytes in marrow or peripheral blood Any additional clonal cytogenetic abnormalities Increasing splenomegaly Extramedullary tumor WBC, platelet count, or hematocrit perturbations not controlled by therapy with hydroxyurea, interferon, or imatinib mesylate Persistent unexplained fever or bone pain Less than 5% blasts in the marrow at time of transplantation Not eligible for OR refused conventional myeloablative allogeneic stem cell transplantation Failed OR suboptimal response to prior imatinib mesylate, as defined by 1 of the following: Absence of complete hematologic response after > 3 months of treatment with imatinib mesylate Absence of cytogenetic response, as defined by 1 of the following: Absence of any cytogenetic response (< 95% Ph+ or BCR/ABL+ cells by cytogenetic or FISH analysis, respectively) after 6 months of treatment with imatinib mesylate Absence of major cytogenetic response (< 35% Ph+ or BCR/ABL+ cells by cytogenetic or FISH analysis, respectively) after 1 year of treatment with imatinib mesylate Absence of complete cytogenetic response (no Ph+ cells by cytogenetic analysis OR BCR/ABL+ cells within normal limits by FISH analysis) after 18 months of treatment with imatinib mesylate Hematologic evidence of disease progression Cytogenetic evidence of disease progression Increase in Ph+ cells or BCR/ABL+ cells by > 20% with at least 1 month between sequential testing Molecular evidence of disease progression More than 10-fold increase in BCR/ABL mRNA levels by quantitative polymerase chain reaction (Q-PCR) with at least 1 month between 2 sequential tests Experienced adverse events during treatment with imatinib mesylate that precluded further administration of the drug No CNS disease refractory to intrathecal chemotherapy HLA identical related donor available Phenotypically matched at HLA-A, -B, -C, DRQ1, and DBQ1 No presence of circulating leukemic blasts by standard pathology PATIENT CHARACTERISTICS: Age Any age Performance status Karnofsky 70-100% OR Lansky 70-100% Life expectancy Not specified Hematopoietic See Disease Characteristics Hepatic No fulminant liver failure No cirrhosis of the liver with evidence of portal hypertension or bridging fibrosis No alcoholic hepatitis No esophageal varices No history of bleeding esophageal varices No hepatic encephalopathy No uncorrectable hepatic synthetic dysfunction evidenced by prolongation of PT No ascites related to portal hypertension No bacterial or fungal liver abscess No biliary obstruction No chronic viral hepatitis AND bilirubin > 3 mg/dL No symptomatic biliary disease Renal Renal failure allowed Cardiovascular No symptomatic coronary artery disease Ejection fraction ≥ 35% No other cardiac failure requiring therapy No poorly controlled hypertension (blood pressure ≥ 150/90 mm Hg) on standard medication Pulmonary DLCO ≥ 30% Total lung capacity ≥ 30% FEV_1 ≥ 30% No requirement for continuous supplementary oxygen No fungal pneumonia with radiological progression after treatment with amphotericin or mold-active azoles for > 1 month Other Not pregnant or nursing Fertile patients must use effective barrier contraception during and for 12 months after completion of study treatment HIV negative No other disease that severely limits life expectancy No other active malignancy except localized nonmelanoma skin cancer No nonhematologic malignancy within the past 5 years that is currently in complete remission and has a > 20% risk of disease recurrence except for nonmelanoma skin cancer No systemic uncontrolled infection No active bacterial or fungal infection unresponsive to medical therapy PRIOR CONCURRENT THERAPY: Biologic therapy See Disease Characteristics Chemotherapy See Disease Characteristics Endocrine therapy Not specified Radiotherapy Not specified Surgery Not specified Other At least 48 hours since prior imatinib mesylate