Myelodysplastic syndromes, from French-American-British to World Health Organization: comparison of classifications on 431 unselected patients from asingle institution
T. Nosslinger et al., Myelodysplastic syndromes, from French-American-British to World Health Organization: comparison of classifications on 431 unselected patients from asingle institution, BLOOD, 98(10), 2001, pp. 2935-2941
In 1999 a working group of the World Health Organization (WHO) published a
revised classification for myelodysplastic syndromes (MDS): RA, RARS, refra
ctory cytopenia with multilineage dysplasia (RC+Dys), RAES I and II, del (5
q) syndrome, and MDS unclassifiable. Chronic myelomonocytic leukemia (CMML)
and RAEB-t were excluded. Standard French-American-British (FAB) and new W
HO classifications have been compared in a series of patients (n = 431) fro
m a single center, analyzing morphologic, clinical, and cytogenetic data. A
ccording to the WHO findings, dysgranulocytopoiesis or dysmegakaryocytopoie
sis only were found in 26% of patients with less than 5% medullary blasts.
These patients are thus unclassified and should remain in the subgroups RA
and RARS. Splitting of heterogeneous RAEB into 2 subgroups according to bla
st count was supported by a trend to a statistically significant difference
in the single-center study population. Patients with CMML whose white bloo
d cell counts are above 13 000/muL may be excluded from the MDS classificat
ion, as warranted by WHO, but a redistribution of patients with dysplastic
CMML according to medullary blast count leads to more heterogeneity in othe
r WHO subgroups. Although the natural courses of RAEB-T and acute myeloid l
eukemia (AML) with dysplasia are different, comparable median survival dura
tions after treatment in patients with RAEB-T and AML were in favor of the
proposed 20% medullary blast threshold for AML. The homogeneity of subgroup
s was studied by evaluating prognostic scores. A significant shift into low
er IPSS risk groups was evident in the new classification. These data canno
t provide evidence for the new WHO proposal, which should not be adopted fo
r routine clinical use at present. Some of its aspects can provide a starti
ng point for further studies involving refined cytogenetics and clinical re
sults. (C) 2001 by The American Society of Hematology.