Natural history and staging of chronic myelogenous leukemia.

The natural history of chronic myelogenous leukemia (CML) has changed in recent years, partly due to earlier diagnosis but mostly as a consequence of the availability of effective therapies that have the potential to eradicate the Philadelphia chromosome-positive clone. Highly effective therapy with imatinib has changed the prognostic significance of clinical features traditionally associated with poor outcome. Achieving a complete cytogenetic response and a major molecular response early during the course of therapy with imatinib may be the most important factor in determining longterm outcome. Therefore, treatment modalities that increase the probability of achieving this goal should be pursued. This article describes the natural history of CML and its prognostic factors,with emphasis on changes due to the emergence of imatinib.