MYELOPROLIFERATIVE DISORDERS - II-CML - CLONAL EVOLUTION AND ITS ROLE IN MANAGEMENT

Twenty-three patients with an established diagnosis of Ph1 positive chronic myelogenous leukemia have been entered into an experimental study to determine the effect on survival of splenectomy and intensive cycle-active chemotherapy based on serial cytogenetic monitoring. Initially, all patients were induced into hematologic remission with busulfan, splenectomized and treated with cytosine arabinoside and 6-thioguanine. Chemotherapy was modified or intensified when abnormal chromosomal patterns were observed in dividing bone marrow cells or non-stimulated short term blood cultures. Elimination or reduction of the abnormal clones was correlated with improved clinical status in the experimental group. Most of the patients who developed abnormal clones prior to clinical evidence of transformation either lost the clone or showed a marked reduction in the size of the clone after aggressive therapy was instituted. The results suggest that survival was prolonged in this group of patients (4-133 months) when compared to historical controls. Pre-selection of patients in the series does not appear to explain the data since 20 of the 23 patients presented with at least one of the poor prognostic factors described by Jacquillat et al. [28] and over 60% of them had two or more of the unfavorable signs at diagnosis. © 1980.