Busulfan and cyclophosphamide versus cyclophosphamide and total body irradiation for marrow transplantation in chronic myelogenous leukemia--a review.

Allogeneic bone marrow transplantation (BMT) for chronic myelogenous leukemia (CML) offers the only significant chance of cure for this disease. About 50% of patients transplanted in the 1980s appear to be cured and with subsequent advances, it is suggested that more patients transplanted in the 1990s will be cured. Cyclophosphamide (Cy) (120 mg/kg) followed by fractionated total body irradiation (TBI) (Cy2/TBI) has been usually employed in preparation for BMT. Alternative regimens of Busulfan (Bu) (16 mg/kg) and Cy (120 mg/kg) (Bu/Cy2) or Bu (16 mg/kg) and Cy (200 mg/kg) (Bu/Cy4) have more recently been employed. At least three studies of Bu/Cy2 or Bu/Cy4 have given encouraging results. Two ongoing randomized studies of Bu/Cy2 versus Cy2/TBI have shown no difference in the event free survival (EFS). In addition, two ongoing randomized studies of Bu/Cy4 versus Cy (200 mg/kg) plus TBI (Cy4/TBI) show no significant differences in EFS. It appears that Bu/Cy regimens are as effective as Cy/TBI regimens. The choice of one regimen over the other depends on matters other than therapeutic efficacy.