OBJECTIVETo establish a nested case-control study cohort in myelodysplastic syndrome (MDS) patients and investigate the clinical characteristics, WHO subtype and risk factors associated with MDS evolution to leukemia of this cohort.

METHODSAll patients, ≥18 years of age, provided by 24 Shanghai hospitals with initial clinical findings consistent with a hematopoietic abnormality between June 2003 and April 2007, were the candidates for inclusion in this study. The blood and bone marrow samples of every patient should be provided at baseline. Diagnosis was made by incorporating morphologic, immunophenotypic, cytogenetic and molecular features according to WHO classification criteria. Cytogenetic analysis was performed using conventional G-banding karyotyping and fluorescence in situ hybridization (FISH) techniques. Cumulative risk of evolution was estimated by Kaplan-Meier method. Prognostic factors were evaluated by univariate Log-rank method and multivariate Cox proportional hazard models.

RESULTSA total of 435 patients were diagnosed as MDS. The median age of MDS onset was 58(18-90) years, with 248 male patients and 187 female patients (male: female 1.33: 1). The percentage of cases with refractory cytopenia with multilineage dysplasia (RCMD) was the highest (65.5%), while that of refraetory anemia (RA) (2.3%), refractory anenia with ring sideroblast (RARS) (1.1%) and 5q-syndrome (0.5%) was lower. Trisomy 8 (+8) was the most common chromosome abnormalities (71 cases, 12.7%). The mean follow-up time was 20.3 (4.2-57.1) months. Cases were patients with evolution by the end of follow-up, while controls were patients without evolution by that time. Case group included 41 patients and control group included 342 patients. Univariate analysis showed that the age, sex, WHO subtype, WBC count, absolute neutrophil count (ANC), IPSS cytogenetic subgroup, IPSS group and bone marrow blast percentage were significant risk factors for leukemia-free survival (LFS). Multivariate analysis of COX model showed that the age, sex, WHO subtype, IPSS cytogenetic subgroup and bone marrow blast were independent risk factors for LFS.

CONCLUSIONA nested case-control study cohort of MDS patients is established. The clinical characteristics and WHO subtype of MDS patients in Chinese Shanghai are different from that in Western countries. The independent risk factors for MDS evolution are age, sex, WHO subtype, IPSS cytogenetic subgroup and bone marrow blast percentage.