Epidemiology of acute promyelocyte leukemia in adult patients

Abstract

International studies report about 40% higher incidence of acute promyelocytic leukemia (APL) in Latino patients than other forms of myeloid leukemia (AML) subtypes, and a lower age of onset. Based on these considerations, we have two main objectives: to establish the distribution of the different subtypes of AML according to age in our country as well as the frequency of APL cases with regards to other subtypes of AML.

Design: Descriptive and retrospective study.

Place and time of the study. Hematology Unit of the School of Medicine, Universidad Nacional de Colombia, between January, 1970 and December. 1999.

Patients and methods: The data were taken from the registry of AML' morphologic diagnosis based on the criteria proposed by the French -AmericanBritish (FAB) Cooperative Group, in patients 14 years old or older.

Statistical methods: Description of patient's age by gender and AML subtype through the mean, and 95% confidence interval. Comparison of patients with APL's age average with other LMA subtypes, by means of an a priori analysis of one ANOVA factor, waging the six subtypes' averages in a single model.

Results: There were 189 patients with AML, with a mean age of 36 years (IC95%, 33.2 38.7). Proportion of APL with regards to other AML subtypes was 12.7%. The a priori contrast of one way ANOVA analysis was + 78.4 WITH t= 3.52, p=0.001, rejecting the null hypothesis of equal mean ages between APL and other AML subtypes.

Discussion. The mean age of Colombian patients with APL is significantly lower than the mean age in patients with other AML subtypes, following the same age pattern reported in international series. The frequency of APL in Colombian patients compared to other AMLs is 12.7%; it is different from the higher incidence rates reported in Latino patients studies carried out in North and South America, and follows the same low frequency reported in clinical trials of AML, 18% (range, 5% to 13%), performed in the United States and Europe. These reports consider the concept of racial distribution of molecular isoforms of the PML gene as the explanation for the differences in AML frequencies among regions.