Impact of conditioning regimen intensity on outcome of allogeneic hematopoietic cell transplantation for advanced acute myelogenous leukemia and myelodysplastic syndrome.

We reviewed 136 patients with advanced acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) undergoing allogeneic transplantation to assess the impact of conditioning regimen intensity on outcome. Thirty-nine patients receiving nonmyeloablative stem cell transplantation (NST) were compared with 97 patients receiving myeloablative transplantation. Patients receiving NST were at high risk for treatment-related complications given that they were older, 57 vs 43 years (P < .001), and more likely had received previous or myeloablative transplantation (54% vs 2%; P < .0001). The cumulative risk of relapse was higher for patients after NST (61% vs 38%; P = .02). The 100-day mortality was less after NST (15% vs 32%) Overall survival (OS) at 2 years was 28% for NST and 34% for myeloablative transplantation (P = .89). Progression-free survival (PFS) at 2 years was 20% for NST and 31% for myeloablative transplantation (P = .31). Cox regression analysis showed that the intensity of the conditioning regimen had no effect on either OS or PFS. Despite the high-risk features of patients with advanced AML or MDS undergoing NST, OS and PFS in these patients was similar to those in patients receiving myeloablative transplantation. These results demonstrate that dose intensity plays a significant role in control of disease after transplantation, but that this benefit is negated by increasing treatment-related mortality. These results suggest that NST is a reasonable alternative for patients with advanced AML and MDS at high risk for complications after myeloablative transplantation.