Geographical Distribution and Cluster Detection of Childhood Leukemia in the Metropolitan Area of Guadalajara, Mexico

Abstract

Background: Acute leukemia is the most common cancer in childhood. Analyzing the spatial distribution of acute leukemia may generate the identification of risk factors. Objective: To study the incidence rate of acute leukemia, its geographic distribution, and cluster detection in the metropolitan area of Guadalajara, Mexico. Methods: We included children under 15 years of age diagnosed with acute leukemia during the period 2010-2014 in the metropolitan area of Guadalajara. Each case was geo-referenced to street level to latitude and longitude coordinates using Quantum Geographic Information System (QGIS). Spatial clusters were found in the location of the acute leukemia cases applying the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm with R statistical software. Results: A total of 269 cases of leukemia were registered, 227 (84%) were acute lymphoblastic leukemia and 42 (16%) acute myeloblastic leukemia. The mean age was 6 ± 4 years. The mean incidence of acute leukemia was 6.44 cases/100,000 inhabitants: El Salto 10.12/100,000, Guadalajara 7.55/100,000, and Tlaquepaque 6.74/100,000. The DBSCAN found three clusters, all located within the municipality of Guadalajara. Conclusions: The incidence of acute leukemia in our population is higher than that in Canada and the USA. We found three spatial clusters of childhood acute lymphoblastic leukemia in the municipality of Guadalajara, suggesting the presence of local predisposing factors. (REV INVES CLIN. 2017;69:159-65)

Temporal trend and spatial distribution of acute lymphoblastic leukemia in Iranian children during 2006 -2014: A Mixed Ecological Study

“…In the present study, 57.9% (2182 patients) of the disease were observed in boys and the sex ratio of males to females was 1.37. These results are consistent with other studies; other studies showed higher incidence of disease in boys than in girls [4,9,[24][25][26]. According to the American Cancer Society's 2019 report, 55 percent of new cases and 56 percent of ALL deaths were boys [27].…”

“…The results of spatial pattern analysis showed that ALL in Iran tended to high spatial autocorrelation and spatial clustering and this clustering was more intense for high values of incidence (hot spots). The emergence of clusters in the assessment of the spatial incidence of ALL has been recognized as an amplifying factor for the influence of environmental risk factors, and especially infectious pathogens, on the disease cycle [7,9,[13][14][15][16]. Among the predisposing, enabling and reinforcing factors that lead to occurrence of leukemia, some researchers suspect the role of viruses (HBV, HCV, HCG, and HTLV-1).…”

“…Spatio-temporal analyses are important tools in monitoring, controlling and surveillance for childhood cancer that can be very effective in generating new hypotheses [6,9,10].Studies on spatial clustering of childhood leukemia can help identify contaminated resources and searching for new clues about environmental risk.…”

“…The question of whether leukemia tends to clustering has become a scientific challenge. Results of published studies are inconsistent; two studies showed no evidence of disease clustering [11,12]; two studies observed significant clustering in at least one subgroup [5,13], and six studies found statistically significant overall clustering [4,7,9,[14][15][16].…”

Geographic Hematology: Some Observations in Mexico

“…In Mexico, no large-scale epidemiologic studies have been conducted in this population, but some studies suggest the incidence of ALL in Mexico is among the highest in the world [16][17][18][19]. The worldwide incidence of ALL varies from 2.0 to 3.5 cases per 100,000 inhabitants per year, whereas in Mexico the incidence is higher than 6/100,000 inhabitants per year [18,20]; the explanation for this difference is unknown. Mexican hematologists were the first to prove that malnutrition is an adverse prognostic factor in children with ALL [21], an observation that has been confirmed worldwide [22].…”