Risk of Transformation to Acute Myeloid Leukaemia and Myelodysplastic Syndromes in Patients With Myeloproliferative Neoplasms Over Attained Age and Time Since Diagnosis: A Nationwide Cohort Study

BACKGROUND: Individuals with polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) face transformation risks to acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). While older age is linked to increased risk, it remains unclear whether risk increases with age or with disease duration. OBJECTIVES: To examine how age and disease duration affect AML and MDS transformation in MPN. METHODS: We used Swedish nationwide register data to model transformation rates as continuous functions of age and disease duration for each subtype and outcome. Cumulative incidences were estimated accounting for competing risk of death. RESULTS: This study included 7156 patients with PV, 6810 with ET, and 1080 with PMF diagnosed in 2001-2021. In PV and ET, AML rates increased with disease duration. In PMF, AML rates were highest soon after diagnosis and declined over time. The 10-year cumulative incidence of AML at diagnosis age 70 was 3.5% in PV, 4.7% in ET, and 18.2% in PMF; for MDS, it was 1.7%, 3.1%, and 10.7%, respectively. CONCLUSION: AML and MDS transformation risks vary by MPN subtype and depend on age and disease duration, with disease duration elevating AML risk in PV and ET; incorporating both factors is essential for individualized risk assessment.