Pretreatment cytokinetic studies in 94 children with acute leukemia. Relationship to other variables at diagnosis and to outcome of standard treatment.

The relationship of the pretreatment bone marrow mitotic index (MI) and in vitro 3H-thymidine labeling index (LI) to other variables present at diagnosis and to the outcome of standard therapy was examined in a series of 94 children with acute leukemia (71 ALL, 23 AML). The range of observed values at diagnosis was extremely broad, from less than 1% labeled cells to more than 25%. The median LI% for all patients studied was 5.2%; the median MI% was 0.3%. The values for AML and ALL did not differ significantly despite older age, higher initial white blood cell (WBC) counts, and poorer response to therapy of AML patients. The initial MI and LI were positively correlated with each other, but unrelated to age or initial WBC count in either ALL or AML. However, the LI and MI were significantly higher (p less than 0.01) in the group of 10 children of 54 studied with ALL whose blasts formed spontaneous rosettes with sheep red blood cells at 37 degrees C. The initial LI and MI were not shown to be related to the likelihood of attaining a complete response or to the length of remission in either ALL or AML. There was thus no evidence that either the initial MI or LI% of marrow blasts was of any prognostic significance in children with acute leukemia.