Molly Tokaz, MD, from Fred Hutchinson Cancer Center, and Lisa Force, MD, MPH, from University of Washington School of Medicine, discuss the recent analysis of worldwide utilization of hematopoietic stem cell transplantation (HSCT) for the treatment of acute myeloid leukemia (AML). Data from this study were recently presented at this year’s American Society of Hematology Meeting & Exposition (ASH 2022).

AML is a rare progressing blood cancer that most often occurs in people over the age of 40 years. Signs and symptoms can vary but for many patients, the cancer can be very aggressive and may require intensive treatment. 

As Dr. Tokaz explains, for many patients with AML, HSCT is the best treatment option; however, it is unclear if certain patient populations have better access to this type of treatment. 

For this analysis, estimates of AML incident cases in 2016 were obtained from the Global Burden of Disease (GBD) 2019 study. HSCT activities were collected from 2009-2016 by the Worldwide Network for Blood and Marrow Transplantation (WBMT) through the European Society for Blood and Marrow Transplantation (EBMT), the Center for International Blood and Marrow Transplantation (CIBMTR), the Asian Pacific Blood and Marrow Transplant Group (APBMT), the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR), the Eastern Mediterranean Blood and Marrow Transplant Group (EMBMT), the Latin American Bone Marrow Transplantation Group (LABMT), the African Blood and Marrow Transplantation Group (AFBMT) and the Cell Therapy Transplant Canada (CTTC). 

The primary endpoint was to analyze the global and regional use and utilization of HSCT (number of HSCT/number of incident cases) for AML. Secondary outcomes included trend from 2009 to 2016, donor type, stem cell source, and remission status.

Global AML incidence was found to have steadily increased, from 101,867 in 2009 to 118,404 in 2016 (+16.2%). Over the same period globally, a 54.9% increase from 9,659 to 14,965 HSCT/year was observed, driven by an increase in allogeneic (+64.9%) with a simultaneous reduction in autologous (-34.9%) HSCT. While highest numbers of HSCT continue to be performed in high-income regions, the largest increases were seen in resource-constrained regions [+94.6% in Africa/East Mediterranean Region] as compared to high-income regions [+34.7% in North America Region]. 

HSCT utilization was skewed towards high-income regions [North America Region 18.4%, Europe 17.9%, South East Asia/Western Pacific Region 11.7%, South America Region 4.5% and Africa/East Mediterranean Region 2.8%]. 

For patients <70 years of age this difference in utilization was widened; North America Region has the highest allogeneic utilization rate, increasing from 2009 to 2016 (30.6% to 39.9%, respectively) with continued low utilization observed in Africa/East Mediterranean Region (1.7% to 2.9%) and South America Region (3.5% to 5.4%, respectively). Patterns of donor stem cell source from related versus unrelated donors varied widely by geographic region. South East Asia/Western Pacific Region has had a +130.2% increase in related donors from 2009 to 2016 and >95% HSCT donors in Africa/East Mediterranean Region are from related HSCT as compared to a predilection for unrelated HSCT in North America Region and Europe. Globally, stem cell source for allogeneic HSCT was predominantly from peripheral blood with increasing use from 2009 to 2016. Autologous HSCT decreased in all regions except in South East Asia/Western Pacific Region (+18.9%)

Overall, the results of this analysis show that allogeneic HSCT for AML is rising globally but marked variations exist in regional utilization and practices, including types of graft source. Resource-constrained regions have the largest increase in HSCT use, but utilization rates remain low with a bias toward familial related donor sources. Further studies are necessary to explain why these differences exist, including economic factors, to understand and address health inequalities and improve discrepancies in the use of HSCT as a potentially curative treatment.

To learn more about AML and other rare cancers, visit checkrare.com/diseases/cancers/