title: Childhood acute leukemias are frequent in Mexico City: descriptive epidemiology.
abstract: BACKGROUND
  Worldwide, acute leukemia is the most common type of childhood cancer. It is particularly common in the Hispanic populations residing in the United States, Costa Rica, and Mexico City. The objective of this study was to determine the incidence of acute leukemia in children who were diagnosed and treated in public hospitals in Mexico City.
  
  
  METHODS
  Included in this study were those children, under 15 years of age and residents of Mexico City, who were diagnosed in 2006 and 2007 with leukemia, as determined by using the International Classification of Childhood Cancer. The average annual incidence rates (AAIR), and the standardized average annual incidence rates (SAAIR) per million children were calculated. We calculated crude, age- and sex-specific incidence rates and adjusted for age by the direct method with the world population as standard. We determined if there were a correlation between the incidence of acute leukemias in the various boroughs of Mexico City and either the number of agricultural hectares, the average number of persons per household, or the municipal human development index for Mexico (used as a reference of socio-economic level).
  
  
  RESULTS
  Although a total of 610 new cases of leukemia were registered during 2006-2007, only 228 fit the criteria for inclusion in this study. The overall SAAIR was 57.6 per million children (95% CI, 46.9-68.3); acute lymphoblastic leukemia (ALL) was the most frequent type of leukemia, constituting 85.1% of the cases (SAAIR: 49.5 per million), followed by acute myeloblastic leukemia at 12.3% (SAAIR: 6.9 per million), and chronic myeloid leukemia at 1.7% (SAAIR: 0.9 per million). The 1-4 years age group had the highest SAAIR for ALL (77.7 per million). For cases of ALL, 73.2% had precursor B-cell immunophenotype (SAAIR: 35.8 per million) and 12.4% had T-cell immunophenotype (SAAIR 6.3 per million). The peak ages for ALL were 2-6 years and 8-10 years. More than half the children (58.8%) were classified as high risk. There was a positive correlation between the average number of persons per household and the incidence of the pre-B immunophenotype (Pearson's r, 0.789; P = 0.02).
  
  
  CONCLUSIONS
  The frequency of ALL in Mexico City is among the highest in the world, similar to those found for Hispanics in the United States and in Costa Rica.
authors.affiliation: Unidad de Investigación en Epidemiología Clínica, Unidad Médica de Alta Especialidad UMAE Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano de Seguridad Social, México DF, México.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Pérez-Saldivar
authors.forename: Arturo
authors.initials: A
authors.lastname: Fajardo-Gutiérrez
authors.forename: Roberto
authors.initials: R
authors.lastname: Bernáldez-Ríos
authors.forename: Armando
authors.initials: A
authors.lastname: Martínez-Avalos
authors.forename: Aurora
authors.initials: A
authors.lastname: Medina-Sanson
authors.forename: Laura
authors.initials: L
authors.lastname: Espinosa-Hernández
authors.forename: José de Diego
authors.initials: Jde D
authors.lastname: Flores-Chapa
authors.forename: Raquel
authors.initials: R
authors.lastname: Amador-Sánchez
authors.forename: José Gabriel
authors.initials: JG
authors.lastname: Peñaloza-González
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Alvarez-Rodríguez
authors.forename: Victoria
authors.initials: V
authors.lastname: Bolea-Murga
authors.forename: Janet
authors.initials: J
authors.lastname: Flores-Lujano
authors.forename: María Del Carmen
authors.initials: Mdel C
authors.lastname: Rodríguez-Zepeda
authors.forename: Roberto
authors.initials: R
authors.lastname: Rivera-Luna
authors.forename: Elisa María
authors.initials: EM
authors.lastname: Dorantes-Acosta
authors.forename: Elva
authors.initials: E
authors.lastname: Jiménez-Hernández
authors.forename: Martha
authors.initials: M
authors.lastname: Alvarado-Ibarra
authors.forename: Martha Margarita
authors.initials: MM
authors.lastname: Velázquez-Aviña
authors.forename: José Refugio
authors.initials: JR
authors.lastname: Torres-Nava
authors.forename: David Aldebarán
authors.initials: DA
authors.lastname: Duarte-Rodríguez
authors.forename: Rogelio
authors.initials: R
authors.lastname: Paredes-Aguilera
authors.forename: María de Los Ángeles
authors.initials: Mde L
authors.lastname: Del Campo-Martínez
authors.forename: Rocío
authors.initials: R
authors.lastname: Cárdenas-Cardos
authors.forename: Paola Hillary
authors.initials: PH
authors.lastname: Alamilla-Galicia
authors.forename: Vilma Carolina
authors.initials: VC
authors.lastname: Bekker-Méndez
authors.forename: Manuel Carlos
authors.initials: MC
authors.lastname: Ortega-Alvarez
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Mejia-Arangure
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D015994:Incidence; D007223:Infant; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000453:epidemiology; D015470:Leukemia, Myeloid, Acute / Q000453:epidemiology*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000453:epidemiology*; D012959:Socioeconomic Factors