Bone M arrow F eatures I mprove P rognostic E fficiency i n Multivariate R isk C lassification o f C hronic-Phase P h 1 1 Chronic M yelogenous L eukemia: A M ulticenter T rial

Results: CART analysis of the validation sample (123 patients with HU therapy) revealed the amount of erythroid precursors in the bone marrow, myelofibrosis, and splenomegaly as the most important prognostic features. Three risk profiles with significantly different survival patterns were established, with median survival times ranging from 33 to 108 months (two-sided log-rank test, P 5 .0001). The new score was confirmed by application to the learning sample with IFN therapy (two-sided log-rank test, P 5 .0002). Furthermore, risk status defined by the new score was significantly correlated with the occurrence of blast transformation. Conclusion: Our data strongly implicate that prognostic classification of chronic-phase Ph 11 CML can be significantly improved by the inclusion of morphologic parameters. The variables of the presented scoring system may be easily assessed by routinely processed aspirates and bone marrow trephines. J Clin Oncol 19:2994-3009. © 2001 by American Society of Clinical Oncology.