Relation between Life Expectancy and Composition of the Bone Marrow at Diagnosis of Chronic Myeloid Leukaemia

The proportions of myeloblasts (MB), promyelocytes (PMC) and myelocytes (MC) within the granulopoietic precursor pool of the bone marrow and a mitotic index of the precursor cells were determined in 43 patients with chronic myeloid leukaemia (CML) diagnosed in the chronic phase of the disease. There was a negative correlation between the percentages of MB + PMC and the mitotic indices, i.e. large proportions of MB + PMC were associated with low mitotic indices. With increasing proportions of MB + PMC at diagnosis, survival was significantly reduced. Furthermore, only 22 % of patients with MB + PMC above the median value (28 %) associated with a mitotic index below the mean value (1.02 %) survived for more than 2 years whereas 82 % of the patients with a percentage of MB + PMC below the median value combined with a mitotic index above the mean value survived for more than 2 years. It is concluded that the composition and mitotic activity of the granulopoietic precursor pool at diagnosis of CML has a prognostic significance. Successive accumulation of early granulocytic precursors with a low mitotic activity probably occurs in the bone marrow during the chronic phase of CML ending up in the final blast crisis characterized by a heavy predominance of such celis.