Monosomal karyotype in acute myeloid leukemia defines a distinct subgroup within the adverse cytogenetic risk category.

Monosomal karyotype (MK) has recently been reported to identify a distinct subset of acute myeloid leukemia (AML) with adverse prognosis. We retrospectively evaluated the frequency of MK in a large cohort of 549 unselected AML cases diagnosed in our department over a period of 13 years and explored potential associations with clinicobiological features and outcome. MK was found in 62 of 549 cases (11.3%), with all but one assigned to the unfavorable cytogenetic risk category; 57 of these 62 MK cases had a complex karyotype. Comparison with a subgroup of AML cases, who had unfavorable karyotypic profiles yet without MK (non-MK) and who were treated uniformly with similar, "3+7"-based regimens, revealed significant (P < 0.05) associations between MK and advanced age, low white blood cell count at diagnosis, and inferior overall survival (6.5 vs. 15 months for non-MK cases). In conclusion, MK defines a sizeable subset of patients with unfavorable cytogenetics who exhibit a distinct clinical profile, even in direct comparison with other unfavorable karyotypes.