Sequential Cytogenetic Analyses of 577 Patients with Myelodysplastic Syndromes: Correlations between Initial Karyotype, Cytogenetic Dynamics, and Clinical Course.

Myelodysplastic syndromes are dynamic diseases presenting with different clinical courses ranging from almost stable courses to rapid progression to acute myeloid leukemias. Karyotype is one of the most important prognostic factors and defines subgroups of favorable, intermediate and adverse prognosis. So far, comparably low attention has been payed on karyotypic changes occuring in sequential cytogentic examinations during the course of the disease. We retrospectively examined karyotypes of 577 patients with MDS or AML with previous history of MDS and at least two successfully performed metaphase analyses. The cytogenetic and clinical data was collected from 5 different centres of the “Kompetenznetz Akute und Chronische Leukaemien” (Duesseldorf, Duisburg, Freiburg, Goettingen, Vienna). Compared to the inital karyotype, karyotype evolution was defined as acquisition of additional aberrations, expansion of an aberrant clone by more than 20% or development of a completely aberrant karyotype after a former mosaic karyotype. According to these criteria, we found karyotype evolution in 155 cases (27%). 2–8 cytogenetic examinations have been performed per case. In 121 cases additional aberrations occured and in 34 cases the aberrant clone expanded in a subsequent analysis. In the group of patients with expansion of the aberrant clone the most frequent karyotypes were 5q- (9x) and +8 (7x). The most frequent aberrant karyotypes later acquiring additional aberrations were complex (22x) and karyotypes with two aberrations (11x), but in the vast majority of cases additional aberrations occurred on basis of a normal karyotype (70x). The most frequent additional aberrations were −7/7q- (23x), 5q- (11x) and +8 (11x). In the group of initially normal karyotypes patients with karyotype evolution had a shorter survivial (p<0.05). In summary, partial or complete momosomy 7 is the most frequent additional aberration in sequential cytogenetic analyses, indicating progression of disease. Due to their genetic instability complex karyotypes or karyotypes with 2 aberrations typically acquire additional anomalies in the course, whereas karyotypes with 5q- and +8 tend to have comparably stable courses. Furthermore, we show that also cases with a normal karyotype can harbour genetic instability as in 12% of all cases a normal karyotype evolved into an aberrant karyotype which was associated with a worse prognosis compared to stable normal karyotypes. Subgroup analyses are necessary to address correlations with therapy, time to AML progression, and the dependency on examination intervals.