Validation of Monosomal Karyotype Based Model In the Risk Stratification of Acute Myeloid Leukemia

The influence of cytogenetic abnormalities on the prognosis of acute myeloid leukemia (AML) has been well-documented; however, the relative impact of certain miscellaneous abnormalities remains controversial. Recently, monosomal karyotype-based risk stratification has been shown to further discriminate the prognosis within the poor-risk karyotype group (Breems et al. JCO 2008), but this finding requires further validation.

We retrospectively reviewed 779 consecutive adult AML patients treated with standard induction chemotherapy, consisting of daunorubicin plus cytarabine (3+7), at our institution from 1998–2008. After excluding patients with favourable risk, normal, missing or failed karyotype, 290 patients remained and were included in the analysis.

The baseline characteristics of these 290 patients were as follows: median age 59 y (range 18–81), male 181, prior malignancy 110, median white cell count (WBC) 7.6 × 10^9/L (range 0–246). The karyotypic features included single monosomy in 42, 2 or more monosomies in 51, and non-monosomy structural and numerical abnormalities in 197 patients. Of the 290, 116 (40 %) had three or more abnormalities (complex karyotype, CK). A total of 141 patients (49 %) achieved complete remission (CR) with 3+7 induction chemotherapy. Sixty-four patients received allogeneic stem cell transplantation in CR. The median overall survival (OS) for all patients was 12 months (95% CI: 10–14 months). The median OS was 10 (95% CI: 6–18), 7 (95% CI: 6–10) and 14 months (95% CI: 12–16) in the single monosomy, 2+ monosomy and non-monosomy groups, respectively (p < 0.0001 by log-rank test comparing the three groups). Among the patients containing at least one monosomy, the OS was not significantly different between the CK and non-CK groups (p = 0.08 by log rank). Similarly, in the non-monosomy structural abnormality group, the OS was not significantly different between the CK and non-CK groups (p = 0.2).

Our results provide validation for the monosomal karyotype-based risk stratification for AML, indicating that patients with at least one monosomy have an inferior OS compared to other poor-risk non-monosomy groups. Within each of the monosomy and non-monosomy groups, the presence of a complex karyotype does not significantly influence the OS.

No relevant conflicts of interest to declare.