Prognostic relevance of cytometric quantitative assessment in patients with myelodysplastic syndromes

Objectives:Morphology and cytogenetics are currently used to define prognosis in myelodysplastic syndromes (MDS). However, these parameters have some limits. Flow cytometry has been recently included in the diagnostic panel for MDS, and its prognostic significance is under evaluation. Methods: Marrow aspirates from 424 MDS patients were analyzed by flow cytometry to evaluate the impact of bone marrow cell immunophenotype on overall survival (OS) and leukemia-free survival (LFS). The immature compartment of myeloblasts was analyzed by the quantitative expression of CD34 (<3% vs. ≥3%), CD117, and CD11b ^-/CD66b ^- (<5% vs. ≥5%); myeloid maturation was analyzed by the expression of CD11b ⁺/CD66b ⁺⁺ (<15% vs. ≥15%) and CD11b ⁺/CD66b ⁺ (<25% vs. ≥25%). Results:  In univariate analysis, the expression of immaturity markers (CD34 ⁺, CD117 ⁺, and CD11b ^-/CD66b ^-) was associated with shorter LFS and OS (P<0.0001); higher expression of differentiation markers (CD11b ⁺/CD66b ⁺⁺ and CD11b ⁺/CD66b ⁺) was associated with longer LFS (P<0.0001 and P=0.0002, respectively) and OS (P<0.0001). In multivariate analysis, expression of CD34 ⁺ (P=0.007), CD117 ⁺ (P=0.013), and CD11b ⁺/CD66b ⁺⁺ (P=0.023) retained independent prognostic value for OS, while only the expression of CD34 ⁺ was a prognostic factor for LFS (P=0.0003). Two different risk groups were defined according to the presence of 0-1 or ≥2 of these factors with significant different LFS and OS (P<0.0001). This score showed prognostic value in predicting survival even in subanalysis according to IPSS and WHO subgroups. Conclusions: Flow cytometric analysis in MDS may provide meaningful prognostic information. Blast percentage expressed as CD117 ⁺ or CD34 ⁺ cells and the quantitative assessment of myeloid maturation showed prognostic value for survival.