During the last 10 years, three European phase II studies were performed to 
investigate the treatment of elderly patients with myelodysplastic syndrome 
(MDS) with low-dose 5-aza-2'-deoxycytidine (decitabine, DAC). All these European 
trial data were reviewed on the basis of the International Prognostic Scoring 
System (IPSS) risk criteria and the response criteria as recently published by 
an international working group. To investigate the results in a larger cohort of 
patients and to determine risk factors, all data were pooled with some 
observations from the PCH 95-06 US phase II study. The response rate in the 177 
patients evaluated (median age 70 years) was 49%. The median response duration 
was 36 weeks, and the median survival was 15 months. Analysis of the data 
according to sex, age, French-American-British classification, percentage of 
blasts in the bone marrow, IPSS risk group, lactate dehydrogenase and 
cytogenetics did not reveal any factor predictive of response. Overall, 69% of 
patients benefited, including those with stable disease during therapy. Response 
duration was significantly shorter with increasing risk (according to the IPSS 
classification). Haemoglobin level and neutrophil count showed an inverse 
correlation to the IPSS classification. Univariate analysis showed a 
significantly inferior survival for elderly patients (>75 years of age) and for 
those with high levels of serum lactate dehydrogenase (LDH) (more than two times 
the normal values). Patients with high-risk cytogenetic abnormalities according 
to the IPSS risk criteria showed better overall survival than those with 
intermediate-risk abnormalities. When analysed according to the IPSS risk 
classification, high-risk patients had worse survival prospects following 
decitabine therapy than those with intermediate risk; however, compared to the 
originally reported IPPS outcomes for high-risk patients, they probably showed 
better survival. During the treatment period, 18% of the patients progressed 
towards acute leukaemia. Decitabine showed a rather low toxicity profile in this 
elderly patient group. In conclusion, low-dose decitabine is an active drug for 
the treatment of MDS patients, even for those older than 75 years with bad 
prognostic characteristics.