Clinical and laboratory data related to maturation in acute leukemia

The relation between the quantified French-American-British cooperative study (FAB) classification and presenting features was studied in 123 adult patients (greater than or equal to 15 years) with acute myeloid leukemia. Myeloblastic leukemia with maturation (M2) patients with a high maturation index (M2a) were older, compared to the other myeloblastic subgroups, while promyelocytic leukemia (M3) patients were younger than those with M2 or M2a. Differences between various leukemia types were found in the occurrence of a preceding myelodysplastic syndrome, leukocyte count, and platelet count. In both monoblastic leukemia (M5) and myeloblastic leukemia (M1-3) a smaller degree of maturation seemed to be related to a larger tumor mass. The effect of chemotherapy was analyzed in a group of 64 patients. Comparison between immature (M1) and more mature (M2) myeloblastic leukemia suggested a longer duration of first complete remission and a longer survival in M2. The findings of this study may imply that the degree of maturation determines tumor mass and the success of chemotherapy.