Diagnostic and prognostic significance of the CFU-c assay in acute nonlymphoblastic leukemia.

A simplified system for classification of aggregate incidence and growth pattern in the CFU-c (colony-forming units in culture) assay, allowing simple and reproducible interpretation of test results, was developed and applied to 552 bone marrow samples from 202 patients with acute leukemia. Ninety-six consecutive patients with acute nonlymphoblastic leukemia were studied at diagnosis. The microcluster growth pattern ("acute myeloid leukemia-type") found in 57% of the patients was significantly associated with higher remission induction rates on both protocols (p = 0.004). No relationship between growth pattern at diagnosis and remission duration was observed. The acute myeloid leukemia-type growth pattern was found to be more frequent in leukemias exhibiting morphological evidence for partial myeloid or monocytic differentiation. The favorable prognostic significance of Auer rods previously described was recognized in two CFU-c growth pattern categories. Of patients exhibiting an acute myeloid leukemia-growth pattern and Auer rods, 89% obtained complete remissions compared to 38% in the Auer rod-negative group showing other growth pattern variants. The CFU-c assays performed during complete remission on 354 samples of 48 patients with acute nonlymphoblastic leukemia and, as a control, on 85 samples of 43 patients with acute lymphoblastic leukemia revealed marked spontaneous as well as chemotherapy-related fluctuations of aggregate incidence and growth pattern. These and similar observations obtained with other assay systems are probably of major pathophysiological significance but preclude clinical application of the CFU-c assay to the monitoring of remission status in patients with acute nonlymphoblastic leukemia.