Evidence for an Underestimation of the Prognostic Impact of Poor Cytogenetics within the IPSS.

In the IPSS the variables bone marrow blasts, cytogenetics and cytopenias were found to be most relevant for clinical outcome by multivariate analysis. Comparing cytogenetics and blasts scoring points were assigned as follows: 0 (good cytogenetics and less than 5% blasts), 0.5 points (intermediate cytogenetics, and 5–10% blasts), 1.0 points (poor cytogenetics), 1.5 points (11–20% blasts), 2.0 (21–30% blasts). In order to examine the correctness of weighting of cytogenetics in comparison to blast counts we compared the survival curves, median survival times (mst) and differences of mst (mst diff.) related to the mst of 37.5 months (mo) of our entire study population (on the basis of 2124 pts. with MDS from our German-Austrian database) between patient subgroups. The results in the subgroups were as follows: Blasts below 5% (n=609) (mst: 58 mo, mst diff.: +20.5 mo), good cytogenetics (n=768) (mst: 55.3 mo, mst diff.: +17.8 mo), blasts 5–10% (n=231) (mst: 28.0 mo, mst. diff.: −9.5 mo), intermediate cytogenetics (n=222) (mst: 28.0 mo, mst diff.: −9.5 mo), blasts: 11–20% (n=160) (mst: 16.5 mo, mst diff.: −21 mo), poor cytogenetics (n=212) (mst: 11.1 mo, mst diff.: −26.3 mo), blasts 21–30% (n=92) (mst: 11.7, mst diff.: −25.7 mo). Our results clearly show that within the IPSS poor cytogenetics are significantly underweighed. Referring to the survival data unfavorable cytogenetics resulted in a survival disadvantage at the same scale as compared to 21–30% blasts. Thus, in a revised IPSS this cytogenetic feature should get the same scoring points as compared to 21–30% blasts when using the FAB-classification. For a scoring system based on the WHO-classification unfavorable cytogenetics should get an even higher scoring value as compared to the maximum blast count of 19%. Further statistical analyses are on the way to substantiate our conclusions.