Classification Systems in MDS
Leukemia Insights - Summer 2007
The most difficult problems in MDS are its morphological diagnosis, access to cytogenetic testing, and therefore application of the different classification systems. These include the FAB1 and WHO2 classifications and the most clinically relevant IPSS3 score. This latter scoring system incorporates percentage of blasts, number of cytopenias and chromosomal alterations to predict overall survival and probability of transformation to AML based on the age of the patient. Despite being more comprehensive and dynamic than the FAB and WHO classifications, it has become apparent that the IPSS has limitations in predicting prognosis of patients with lower-risk MDS. Also several groups have now presented data with more refined cytogenetic classifications4.
Based on these, we are currently developing a new classification system for patients with lower risk disease. To do this we studied close to 900 patients referred to our center over the last 25 years with low or intermediate-1 MDS (by the IPSS score) that had not received therapy. The first important observation was that 10% of patients eventually transformed to AML. This indicates the need to treat patients with lower-risk MDS. Second, we have developed a scoring system that allows us to separate these patients with lower risk MDS into three subgroups (Figure 1): 80 % of patients will survive less than 2 years after referral without therapy. This data is of great importance as many of these patients are currently observed and not treated. The validation of this data would provide a frame work for introducing new agents in MDS.