Unrelated Donor Allogeneic Hematopoietic Cell Transplantation Is Underused as a Curative Therapy in Eligible Patients from the United States

Allogeneic hematopoietic cell transplantation (alloHCT) is a curative therapy for hematologic disorders including acute lymphoblastic and myeloid leukemia, chronic lymphocytic and myeloid leukemia, Hodgkin's and non-Hodgkin lymphoma, multiple myeloma, and myelodysplastic syndrome. To determine the utilization of alloHCT from unrelated donors (URDs) in the United States, we calculated the number of patients diagnosed with hematologic disorders age 20 to 74 years based on 2004 to 2008 Surveillance, Epidemiology and End Results and 2007 US Census data, estimated the percentage of patients who would be eligible for URD alloHCT after discounting the mortality rate during induction therapy and the rate of severe comorbidities, and compared these with the actual 2007 alloHCTs facilitated by the National Marrow Donor Program. We found that the number of URD alloHCT as a percentage of the estimated potential transplantations ranged from 11% for multiple myeloma to 54% for chronic myeloid leukemia, with an average percentage of 26% for all the disorders considered. In an analysis stratified by age groups (20 to 44, 45 to 64, and 65 to 74 years), the utilization of URD alloHCT was higher in younger patients than in older patients for all disorders. Of acute lymphoblastic and myeloid leukemia patients, approximately 66% underwent URD alloHCT later in the course of their disease (in second or greater complete remission). URD alloHCT is likely underused for potentially curable hematologic disorders, particularly in older patients. Understanding the reasons for low use of alloHCT may lead to strategies to expand the use of this curative therapy for more patients with hematologic disorders.