Acute lymphoid and myeloid leukemia in a Brazilian Amazon population: Epidemiology and predictors of comorbidity and deaths

Abstract

Introduction: Leukemia is the most common cancer in children and has the highest rates of incidence in industrialized countries, followed by developing countries. This epidemiologic profile can mainly be attributed to the availability of diagnostic resources. In Brazil, leukemia diagnosis is a challenge due to financial viability, lack of hemovigilance services in isolated regions and the vast size of the territory. Its incidence in the state of Amazonas has been increasing since 2010. Therefore, this study aims to describe the epidemiological pattern and spatial distribution of patients with acute lymphoid leukemia and acute myeloid leukemia in Amazonas and identify the predictors of comorbidity and death.

Materials and methods: A retrospective cross-sectional study was carried out based on patients' data which was obtained from the database of a referral center for the period of 2005 to 2015. Variables included age, gender, ethnicity, civil status, schooling, income, location of residence, subtype of leukemia, comorbidities, and date of death. The spatial distribution was performed using QGIS v.2.18. Stata software was used for univariable and multivariable logistic regression to evaluate the association between both comorbidities and death for all characteristic groups of ALL and AML.

Results: The group that was studied was composed of 577 ALL and 266 AML patients. For both, most patients were male, with a schooling period of 1-4 years, received<1 minimum wage, and lived mostly in Manaus, followed by the municipality of Tefé. There was no association between the development of comorbidities and analyzed variables in patients with ALL. AML patients that were >60 years old and with family history of the disease had the highest risk of developing comorbidities (OR = 5.06, p = 0.038; OR = 2.44, p = 0.041, respectively). Furthermore, patients with ALL and in the 41-50-year age group had a higher risk of death (OR = 31.12; p = 0.001). No association between death and explanatory variables were found in patients with AML. In addition, significant difference was observed in time to death (chi2 = 4,098.32, p = 0.000), with 50% of patients with AML dying within two years after diagnosis, whereas in ALL, this percentual of death only is reached in approximately 5 years.

Conclusion: Our study describes the data of patients with acute leukemia in Amazonas, a remote region in the north of Brazil. In addition, it highlights the importance of hemovigilance in an Amazon region state, while focusing on peripheral areas which don't have prevention, diagnosis and treatment tools for this disease.

Fig 1. Spatial distribution by municipality in Amazonas and number of cases and death per year of acute leukemia patients diagnosed between 2005 and 2015.

a) ALL patient distribution. b) AML patient distribution. c) Number of cases and deaths of ALL patients per year of study. d) Number of cases and deaths of AML patients per year of study.

Fig 2. Time to death in 10 years after diagnosis for both types of acute leukemia patients (ALL and AML).

Kaplan-Meier method was used for survival analysis demonstrating that the time to patient death in the AML was different from that of the ALL (N = 843, Deaths = 421, Median = 583 (days), Range = 1–3650 (days), chi² = 4,098.32, p = 0.000). Furthermore, statistical analysis was performed with log-rank test for comparison between groups.