[1410] Refractory Anemia with Excess Blasts in Transformation Exhibits Clinicopathologic Features and Clinical Behavior Similar to AML with ≥30% Blasts

Veronica Klepeis, Robert P Hasserjian. Massachusetts General Hospital, Boston, MA

Background: A major change in the 2001 WHO Classification of Myeloid Neoplasms was elimination of the FAB myelodysplastic syndrome (MDS) category of refractory anemia with excess blasts in transformation (RAEBT) and the definition of acute myeloid leukemia (AML) as ≥20% blood or bone marrow (BM) blasts. However, the recently revised International Prognostic Scoring System (IPSS-R) of MDS considers cases with 10-29% BM blasts within one category based on some studies showing that MDS/AML with 10-19% and 20-29% blasts have similar prognosis.
Design: We identified newly diagnosed MDS/AML cases within the IPSS-R 10-29% bone marrow blast count stratum and compared cases with 10-19% blasts (RAEB2, n=21) to those with 20-29% blasts (RAEBT, n=22), as well as to a control group of newly diagnosed AML with ≥30% blasts (n=125). Cases with inv(16), t(15;17), or t(8;21) and therapy-related neoplasms were excluded from all groups.
Results: RAEB2 patients (p=0.004), but not RAEBT patients were significantly older than AML patients. High-risk karyotypes (complex or abnormalities of chromosomes 5 and 7) were more frequent in the RAEB2 group, but this was not statistically different from RAEBT or AML. Overall survival (OS) of RAEB2 patients was inferior to AML (p=0.009), while OS of AML and RAEBT were similar. AML patients were more frequently treated aggressively (by induction chemotherapy or bone marrow transplantation) than RAEB2 (p=0.006) but not RAEBT (p=0.13) patients. While aggressive therapy did not significantly influence OS of RAEB2 patients (p=0.7), OS of both RAEBT (p=0.01) and AML (p<0.0001) patients treated aggressively were superior to those treated with low-intensity or supportive therapies.

Features of RAEBT, RAEB2 and AML
Median age (years)69*6560
Median marrow cellularity60%*80%90%
High-risk karyotype11/21 (52%)8/22 (36%)44/123 (36%)
Treated with aggressive therapy10/21 (48%)*15/22 (68%)105/125 (84%)
Median OS, all patients (months)11*1216
Median OS, high-intensity therapy (months)11*2021
Median OS. low-intensity/supportive therapy (months)9103
*Significantly (p<0.05) different from AML

Conclusions: Our data suggest that RAEBT displays clinicopathologic features similar to AML with ≥30% BM blasts. Unlike RAEB2 patients, RAEBT patients treated agressively exhibit superior survival to those treated with low-intensty/supportive therapies. While these data require confirmation in a larger series of patients, they suggest that RAEBT should continue to be considered within the category of AML.
Category: Hematopathology

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 225, Wednesday Morning


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