Population-Based Analysis of Outcomes in Acute Myeloid Leukemia from a Provincial Cancer Registry and the Canadian Cancer Registry: A Population-Based Retrospective Cohort Study
Authors: Abduallah Yaqeen , Sriranjan Neelan , Paulson Kristjan , Houston Brett L. 
Published: December 2024

Background: Acute myeloid leukemia (AML) is the most common acute leukemia in adults, accounting for approximately 80 % of cases in adults. The age-standardized incidence rate in Canada is 3.46 cases of AML per 100,000 person-years. Despite advances in therapeutic modalities, the prognosis of AML remains guarded. The landscape of AML management has changed in recent years, due to advancements in molecular diagnostics, targeted therapies, and transplantation. A comprehensive understanding of its epidemiology and outcomes is necessary for informed clinical decision-making.

Methods: This retrospective cohort study aimed to comprehensively assess the outcomes and examine two-year relative survival in individuals diagnosed with AML between 1990 and 2014 in Manitoba and between 1995 and 2014 in Canada. Two-year relative survival was chosen as the outcome of interest because it describes survival during the transition away from direct cancer care back to community care and follow-up. This provides an estimate of the effect of AML on mortality by removing the impact of other causes of death.

We analysed the Canadian Cancer Registry (CCR), which contains data on all Canadians with AML. To provide clinical information lacking in the CCR, we obtained data from the Manitoba Cancer Registry (MCR). Data from the MCR added cytogenetic data and therapeutic implications such as the use of azacitidine and receipt of a bone marrow transplant. Comprehensive analyses revealed key demographic trends, such as age distribution and gender disparities.

Results: There were 18,975 individuals included in the analysis with all of Canada and 785 individuals included in the Manitoba-only analysis. Baseline demographics of the Canadian cohort and Manitoba cohorts were similar, with few exceptions. In both cohorts, approximately 55 % of each cohort were male. The percent of individuals in the cohort increased with age at diagnosis. In Canada, 81 % of individuals lived in urban regions, whereas only 71 % of individuals in Manitoba lived in urban regions.

Overall, there was a 2% decrease in excess mortality for each increase in diagnosis year in both cohorts studied. This demonstrates a steady improvement in AML outcomes over time and highlights our advancements in care for patients with AML over the years. Additionally, in the Canadian cohort, there was a 9 % decrease in excess mortality for individuals who live in urban regions. This improved survival in patients in an urban setting as compared to those in a rural setting may be attributed to increased access to cancer treatment facilities and emergency resources in urban regions.

Conversely, when looking at individuals diagnosed in Manitoba only, there was no evidence of a difference in excess mortality for rurality. The data from the provincial registry expectedly demonstrated a 48 % decrease in excess mortality for individuals who received a bone marrow transplant. Advances in supportive care measures have importantly reduced mortality rates after transplantation. There was no evidence of a significant difference in excess mortality with azacitidine use.

Conclusion: There is a steady improvement in AML survival rates over the study period, reflecting advancements in therapy and supportive care. Notably, there is improved survival rates in urban patients compared to their rural counterparts, highlighting the importance of addressing geographical differences in healthcare access and equity.