Comparison of FAB and WHO Classifications and Validation of WHO Classifications in 218 Korean Patients with Myelodysplastic Syndrome / 대한진단검사의학회지

ABSTRACT

BACKGROUND: World Health Organization (WHO) proposed a new classification of myelodysplastic syndrome (MDS) in 1999, based on significant modifications of the original FAB proposals. The aim of the present study was to validate the new classification with respect to prognostic importance. METHODS: Two hundred and eighteen patients were diagnosed with MDS according to the FAB criteria between August 1989 and June 2001 in the Asan Medical Center. They were studied retrospectively to evaluate morphological, clinical and cytogenetic data for diagnosis and clinical outcomes with long-term follow up, and reclassified with a new WHO classification. RESULTS: According to the original FAB classification, 218 patients were classified as RA 78, RARS 17, RAEB 76, RAEB-t 38 and CMML 9. They were reclassified to the WHO classification to RA 24, RARS 6, RCMD 51, RCMD-RS 11, RAEB-1 42, RAEB-2 51, del(5q) syndrome 1 and unclassifiable 2. Twenty-one cases of RAEB-t and 9 cases of CMML were reclassified to acute myeloid leukemia and myelodysplastic syndrome/myeloproliferative disease (MDS/MPD). Among the reclassified groups in the WHO classification, there is a significant difference in prognosis between RA and RCMD (median survival, not reached vs. 28.4 months, P=0.020), and in leukemic transformation between RAEB-1 and RAEB-2 (5% vs. 37%, P=0.001). CONCLUSIONS: These data provide the proper evidence, especially of prognosis and leukemic transformation for the WHO classifications. We recommended using the WHO classification rather than the FAB classification of the diagnosis of MDS.