The new diagnostic criteria for myelodysplasia-related acute myeloid leukemia is useful for predicting clinical outcome: comparison of the 4th and 5th World Health Organization classifications.

Mutations in myelodysplasia-related (MR) genes, rather than morphological features, have been included in the diagnostic criteria of the new 5th World Health Organization (WHO) classification for myelodysplastic syndrome (MDS)-associated acute myeloid leukemia (AML). This study compares the clinical relevance of the new criteria with those of the previous version. In a cohort of 135 patients with newly diagnosed AML, the MDS-related AML patients were classified according to the 5th and 4th edition of the WHO classification (AML, myelodysplasia-related [AML-MR 5th ] and AML with myelodysplasia-related changes [AML-MRC 4th ], respectively). The median age of the patients was 70.4 years. MR gene mutations were found in 48 patients (35.6%). Sixty-one patients (46.6%) were diagnosed with AML-MRC 4th , while 71 patients (53.0%) were diagnosed with AML-MR 5th . Patients with AML-MR 5th were significantly older with significantly lower treatment response rate, higher recurrence rate, and shorter relapse-free survival after chemotherapy, whereas AML-MRC 4th patients did not show any association with the treatment outcome. Overall, the following prognostic factors for survival were identified: age over 75 years, antecedent MDS or MDS/myeloproliferative neoplasm, chromosome 5 or 7 abnormalities, and KRAS and ZSZR2 mutations. The 5th WHO classification is more useful for predicting the treatment response of patients with AML-MR than the previous version. Among the MR genes, ZSZR2 mutations were found to be independent prognostic factors affecting survival.