Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Elderly Patients with Myeloid Malignancies Over 70 Years Old: A Retrospective Analysis of the Japanese Nationwide Registry.

Although allogeneic hematopoietic stem cell transplantation (SCT) remains a potentially curative treatment option for several myeloid malignancies, despite the fact that the average age at disease onset for myeloid malignancies is approximately 70 years of age, its applicability in elderly patients is challenging. We retrospectively evaluated the outcomes of elderly SCT patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), using a nationwide Japanese registry database. We analyzed the data of 3609 patients ranging from 65 to 79 years of age with AML or MDS who underwent initial SCT between 2003 and 2022, while focusing on those 70 to 74 (n = 645) and 75 to 79 years old (n = 65). The 2-year overall survival (OS) and relapse-free survival rates for patients aged 65 to 69, 70 to 74, and 75 to 79 years were 40.9%, 38.0%, and 22.7%, and 48.4%, 47.2%, and 18.5%, respectively. Among patients categorized as low-risk at SCT, no significant differences were observed in the cumulative incidence of grade III to IV acute graft-versus-host disease (aGVHD), extensive chronic GVHD (cGVHD), non-relapse mortality, or relapse across all age groups. A multivariate analysis revealed that sex (male), diagnosis (AML), disease status (high-risk), SCT year (2003 to 2007), performance status (2-4), hematopoietic cell transplantation-specific comorbidity index (≥3), development of grade III to IV III-IV aGVHD, and extensive chronic GVHD significantly affected the OS. An older age (75 to 79) and the intensity of conditioning (reduced intensity) were factors indicating a trend toward an adverse prognosis. In these subgroups, significant interactions were observed between OS and SCT years, the time from diagnosis to SCT, and aGVHD. These findings suggest that SCT may be a potential curative option for selected elderly patients up to the mid-70s; however, careful patient selection and vigilant management of aGVHD are crucial factors for improving outcomes.