Prognostic Significance of Unbalanced Chromosome Abnormalities Used by 2008 World Health Organization (WHO) Classification to Define 'Acute Myeloid Leukemia (AML) with Myelodysplasia-Related Changes' in Adults: a Cancer and Leukemia Group B (CALGB) Study

Abstract 2602 Poster Board II-578 One of the major revisions in the 2008 WHO classification of “AML and Related Precursor Neoplasms” is the use of certain cytogenetic abnormalities (abns) as a criterion for inclusion in the “AML with myelodysplasia-related changes” category. These abns include 9 specific reciprocal translocations, 8 unbalanced abns, and complex karyotypes (CK), ie, ≥3 unrelated abns. The clinical features and outcome of patients (pts) with these abns require further study to confirm the appropriateness of their inclusion in this WHO category. Therefore, we evaluated 2,724 consecutive untreated adults meeting criteria for possible inclusion in this WHO category (ie, non-therapy-related AML and not part of the first WHO AML category) in the CALGB cytogenetics database; 516 (19%) pts harbored ≥1 myelodysplasia-related abn and/or CK, and had outcome data available. Their median age was 62 years (y; range, 15–88 y). The 9 reciprocal translocations were very rare, with t(3;5)(q25;q34) found in 6 pts, t(3;21)(q26.2;q22.1) in 2, t(1;3)(p36.3;q21.1) and t(2;11)(p21;q23) in 1 pt each and the remaining 5 translocations not detected. Their rarity precluded further analyses. With the exception of idic(X)(q13), found in 2 pts, the remaining 7 unbalanced abns were more common (Table). Importantly, the abns were not mutually exclusive, ie, ≥2 different abns could co-exist in the same karyotype and/or be part of a CK. Among 453 pts with ≥1 specific unbalanced abn (Table), 62% had CK; the highest % of CK, 89–95%, were seen in the i(17q) or t(17p), −13 or del(13q) and −5 or del(5q) groups and the lowest, only 24%, in del(9q) pts. As a group, non-CK pts had a higher complete remission (CR) rate (P=.002) and longer overall survival (OS; P Disclosures: No relevant conflicts of interest to declare.