The regimen-related toxicity (RRT) of a busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) conditioning regimen (BuCy) was evaluated in 70 consecutive patients undergoing allogeneic bone marrow transplantation for hematologic malignancies. Patients were given toxicity gradings retrospectively in each of eight organ systems (cardiac, bladder, renal, pulmonary, hepatic, CNS, stomatic, and gastrointestinal) according to a recently developed RRT scale. A set of patient, disease, and treatment parameters (age, sex, diagnosis, Eastern Cooperative Oncology Group [ECOG] score, preconditioning liver function tests [LFT], prior chemotherapy exposure, disease status, graft-versus-host disease [GVHD] prophylaxis, antimicrobial agent use, hematologic recovery, and severity of acute GVHD) was statistically analyzed to determine significant predictors of RRT. The most common significant organ toxicities were stomatic (87% of patients; 63% grades II to IV) and hepatic (83% of patients; 44% grades II to IV). Renal and gastrointestinal toxicities were not uncommon (35% and 27%, respectively) but were rarely serious (9% and 1% grades II to IV, respectively). Twelve patients developed grade III toxicities of the following systems: hepatic (seven), pulmonary (two), bladder (two), and CNS (one). Females had more frequent stomatitis (P = .04) and hepatic RRT (P = .004). Patients receiving methotrexate in their GVHD prophylactic regimen experienced more grade II to IV stomatitis (P = .04) and hepatic RRT (P = .04). The use of amphotericin B (P = .01) or prolonged antibiotic courses (P = .04) was associated with more grades II to IV hepatic RRT. In a multivariate analysis, only amphotericin B administration predicted grades II to IV hepatic RRT (P = .01). The incidence of acute GVHD was 49%, with 31% having grades II to IV GVHD. The estimated 2-year event-free survival (EFS) for the entire study group was 44%. The estimated 2-year EFS was 63% for standard-risk patients (acute leukemia in first remission and chronic myelogenous leukemia [CML] in first stable phase) and 24% for all others (high-risk patients). High-risk patients were at increased risk of disease recurrence and RRT. BuCy is an efficacious bone marrow transplant conditioning regimen for standard-risk patients with leukemia but has significant associated hepatic RRT.
