title: Predictors of outcome and methodological issues in children with acute lymphoblastic leukaemia in El Salvador.
abstract: BACKGROUND
  Most children with cancer live in low-income countries (LICs) where risk factors in paediatric acute lymphoblastic leukaemia (ALL) developed in high-income countries may not apply.
  
  
  METHODS
  We describe predictors of survival for children in El Salvador with ALL. We included patients <16 years diagnosed with ALL between January 2001 and July 2007 treated with the El Salvador-Guatemala-Honduras II protocol. Demographic, disease-related, socioeconomic and nutritional variables were examined as potential predictors of event-free survival (EFS) and overall survival (OS).
  
  
  RESULTS
  260/443 patients (58.7%) were classified as standard risk. Standard- and high-risk 5-year EFS were 56.3 ± 4.5% and 48.6 ± 5.5%; 5-year OS were 77.7 ± 3.8% and 61.9 ± 5.8%, respectively. Among standard-risk children, socioeconomic variables such as higher monthly income (hazard ratio [HR] per $100 = 0.84 [95% confidence interval (CI) 0.70-0.99; P=0.04]) and parental secondary education (HR = 0.49, 95% CI 0.29-0.84; P = 0.01) were associated with better EFS. Among high-risk children, higher initial white blood cell (HR per 10×10(9)/L = 1.03, 95% CI 1.02-1.05; P<0.001) predicted worse EFS; socioeconomic variables were not predictive. The difference in EFS and OS appeared related to overestimating OS secondary to poor follow-up after abandonment/relapse.
  
  
  CONCLUSIONS
  Socioeconomic variables predicted worse EFS in standard-risk children while disease-related variables were predictive in high-risk patients. Further studies should delineate pathways through which socioeconomic status affects EFS in order to design effective interventions. EFS should be the primary outcome in LIC studies.
authors.affiliation: Paediatric Oncology, Benjamin Bloom National Children's Hospital, San Salvador, El Salvador.
authors.forename: Miguel
authors.initials: M
authors.lastname: Bonilla
authors.forename: Sumit
authors.initials: S
authors.lastname: Gupta
authors.forename: Roberto
authors.initials: R
authors.lastname: Vasquez
authors.forename: Soad L
authors.initials: SL
authors.lastname: Fuentes
authors.forename: Gladis
authors.initials: G
authors.lastname: deReyes
authors.forename: Raul
authors.initials: R
authors.lastname: Ribeiro
authors.forename: Lillian
authors.initials: L
authors.lastname: Sung
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D004544:El Salvador / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000401:mortality*; D011379:Prognosis; D012307:Risk Factors; D012959:Socioeconomic Factors