OBJECTIVETo investigate leukemia transformation rate in myelodysplastic syndrome (MDS) and the relationship with quantitative and type of chromosomal abnormality.

METHODSThis study retrospectively analyzed and rediagnosed 138 MDS patients with complete data, investigated the rate and time of leukemia transformation, and analyzed characteristics of chromosome karyotype of de novo patients.

RESULTS29 (21.01%) of 138 patients transformed into leukemia, the rate and the median time of leukemia transformation were 21.01% and 8 (3-24) months, respectively, among which, the rate of leukemia transformation in normal karyotype, abnormal karyotype analysis of ≤5 mitotic cells, and >5 mitotic cells in split phase groups were 6.2%, 23.8% and 38.5%, respectively, and median time of which were 17(13-22), 13(5-23), and 7(3-10) months, respectively. Increased trend of leukemia conversion rate along with increased quantity of chromosomal abnormality was observed (χ²=14.185, P＜0.01). Leukemia transformation time negatively correlated with quantity grade of abnormal karyotype (r=-0.631, P<0.01), The leukemia transformation rates in monosomy 7/del 7q, trisomy 8, trisomy 11, complex karyotype and normal karyotype groups were 65.0%, 50.0%, 30.8% and 28.6%, being significantly different (χ²=21.555, P<0.01). Leukemia transformation rate of complex karyotype and monosomy 7/del 7 q was slightly higher than of trisomy 8 and trisomy 11, but both of them were significantly higher than of normal karyotype (χ²=8.054, P=0.005). There were no leukemia transformation cases in del 5q, del 20q, monosomy Y, and trisomy 21 group.

CONCLUSIONWith or without abnormal chromosome karyotype, quantity and types of abnormal karyotype had important clinical value to predict leukemia transformation in patients with MDS.