Busulfan Plus Cyclophosphamide Compared with Total-body Irradiation Plus Cyclophosphamide Before Marrow Transplantation for Myeloid Leukemia: Long-term Follow-up of 4 Randomized Studies

In the early 1990s, 4 randomized studies compared conditioning regimens before transplantation for leukemia with either cyclophosphamide (CY) and total-body irradiation (TBI), or busulfan (Bu) and CY. This study analyzed the long-term outcomes for 316 patients with chronic myeloid leukemia (CML) and 172 patients with acute myeloid leukemia (AML) who participated in these 4 trials, now with a mean follow-up of more than 7 years. Among patients with CML, no statistically significant difference in survival or disease-free survival emerged from testing the 2 regimens. The projected 10-year survival estimates were 65% and 63% with Bu-CY versus CY-TBI, respectively. Among patients with AML, the projected 10-year survival estimates were 51% and 63% (95% CI, 52%-74%) with Bu-CY versus CY-TBI, respectively. At last follow-up, most surviving patients had unimpaired health and had returned to work, regardless of the conditioning regimen. Late complications were analyzed after adjustment for patient age and for acute and chronic graft-versus-host disease (GVHD). CML patients who received CY-TBI had an increased risk of cataract formation, and patients treated with Bu-CY had an increased risk of irreversible alopecia. Chronic GVHD was the primary risk factor for late pulmonary disease and avascular osteonecrosis. Thus, Bu-CY and CY-TBI provided similar probabilities of cure for patients with CML. In patients with AML, a nonsignificant 10% lower survival rate was observed after Bu-CY. Late complications occurred equally after both conditioning regimens (except for increased risk of cataract after CY-TBI and of alopecia with Bu-CY).