Prediction of Survival in Patients with Myelodysplastic Syndrome According to WHO Classification-Based Prognostic Scoring System (WPSS).

Background Based upon the classification of FAB criteria, International Prognostic Scoring System(IPSS) has been a standard prognostic model to predict survival and progression in MDS. In 2000, the WHO has formulated a new classification of myelodysplastic syndrome(MDS). The aim of this study was to evaluate the prognostic value of WHO classification-based prognostic scoring system(WPSS) in MDS.

Patients and methods One hundred forty-nine patients who were diagnosed as having de novo MDS at the Division of Hematology-Oncology, Samsung medical center, Seoul, Korea, between Dec. 1994 and Feb. 2007, were evaluated retrospectively for clinical and hamatologic features at diagnosis, transfusion dependence, overall survival(OS), and progression to leukemia(LFS). Risk group stratifications in MDS patients were done according to IPSS and WPSS.

Results 18 patients(12.1%), 93 patients (62.4%), 29 patients(29%) and 9 patients(6%) had IPSS risk scores of low, intermediate-1(Int-1), intermediate-2(Int-2) and high, respectively. According to WPSS risk scores, 8 patients(5.4%), 30 patients(20.1%), 41 patients(27.5%), 57 patients(38.3%) and 13 patients(8.7%) were classified to very low, low, intermediate, high and very high risk group, respectively. In IPSS, median OSs of low, Int-1, Int-2 and high subgroup were 65.2, 32.9, 14.3 and 9.1 months respectively (p<0.001). According to WPSS, median OSs of very low, low, intermediate, high and very high risk subgroup were not reached, 55.4, 27.4, 19.0 and 6.2 months respectively (p<0.001). Between subgroups classified according to WPSS, significant differences in OS were noted in low vs. intermediate risk group (p=0.047), in intermediate vs. high risk group (p=0.046) and in high vs. very high risk group(p=0.003) but statistically not significant difference in OS was observed between very low and low risk group (p=0.08). The mean and median OS of the lowest risk group(low risk) in IPSS are 65.33 and 55.43 months, respectively. The mean and median OS of the lowest risk group(very low risk) in WPSS are 102.8 months and not reached, respectively.

Conclusion These data show that WPSS with five risk groups might provide more refined prognostic stratifications of MDS than IPSS with four risk groups. Especially, new prognostic system appears to discriminate a subset of patients with very low risk, who could have long term survival.