Original Study Evaluation of Parameters Related to the Probability of Leukemic Progression in Patients With Lower-Risk Myelodysplastic Syndrome Jose F. Falantes, Francisco J. Márquez-Malaver, Cristina Calderón-Cabrera, Begoña Pedrote, María L. Martino, Jose González, Ildefonso Espigado, Jose A. Pérez-Simón Abstract Several prognostic factors such as intermediate karyotype, presence of 5% to 9% bone marrow blasts, and platelet count <50 3 10e 9 /L are related to the probability of leukemic progression in a cohort of patients with lower-risk myelodysplastic syndrome. Background: The prognosis of patients with lower-risk myelodysplastic syndrome (LR-MDS) is very heterogeneous. In addition to survival estimates, identification of factors related to the probability of leukemic progression might help prognosis assessment. Patients and Methods: The present study is a retrospective analysis of 409 patients with primary LR-MDS. The probability of leukemic progression was estimated in the competing risk framework by the cumulative incidence method considering death without acute myeloid leukemia (AML) as a competing event. Results: Sixty-six patients (16.1%) progressed to AML. The following covariates influenced the probability of leukemic progression in a multivariate competing risk regression model: intermediate karyotype versus diploid or chromosome 5 deletion, 5% to 9% bone marrow blast percentage, platelet count <50  10e 9 /L and age younger than 75 years. Conclusion: According to these, a predictive model is proposed, which categorizes patients with different probability of leukemic progression (P < .001). Validation of these results might help prognostic refinement of patients with LR-MDS. Clinical Lymphoma, Myeloma & Leukemia, Vol. -, No. -, --- ª 2018 Elsevier Inc. All rights reserved. Keywords: Acute myeloid leukemia, Competing risk analysis, Predictive model, Prognosis, Score Introduction Myelodysplastic syndromes (MDS) are defined as a group of clonal hematopoietic disorders characterized by dysplastic features in the bone marrow, ineffective hematopoiesis resulting in peripheral cytopenia, and eventual risk of progression to acute myeloid leu- kemia (AML). 1-3 The prevalence of MDS increases with age, affecting mainly older individuals with a median age at diagnosis of older than 70 years. 4 For treatment approaches, patients with the low and intermediate-1 categories according to the International Prognostic Scoring System (IPSS) 5 are defined as having lower-risk disease (LR-MDS). However, within this LR-MDS subgroup there is a wide clinical heterogeneity as shown by the prognostic refine- ment of the revised IPSS (IPSS-R), 6 together with the development of specific prognostic models for patients with lower risk disease. 7-10 These prognostic models consider age, severity of cytopenias, transfusion dependency, karyotype other than diploid or chromo- some 5 deletion, and increase of bone marrow blasts for a better stratification in this set of patients. In addition to survival estimates, prognostic assessment for patients with LR-MDS must consider the eventual risk to leukemic progression. Classical prognostic scoring systems such as the IPSS 5 and the IPSS-R 6 have been used to evaluate the median time to AML evolution of patients with MDS. However, most patients categorized as low and intermediate-1 risk categories according to the IPSS or the very low, low, and inter- mediate categories according to the IPSS-R 6 died without evidence of evolution to AML, with infection, hemorrhage, and worsening of cytopenias being the most frequent causes of death. 11-14 With this Department of Hematology, University Hospital Virgen del Rocío, Seville, Spain Submitted: Feb 18, 2018; Revised: Apr 19, 2018; Accepted: May 2, 2018 Address for correspondence: Jose F. Falantes, MD, Department of Hematology, University Hospital Virgen del Rocío, Avenida Manuel Siurot s/n, 41013 Seville, Spain E-mail contact: josef.falantes.sspa@juntadeandalucia.es 2152-2650/$ - see frontmatter ª 2018 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.clml.2018.05.004 Clinical Lymphoma, Myeloma & Leukemia Month 2018 - 1