1. ¹Division of Epidemiology, University of Minnesota School of Public Health, Minneapolis, MN 55454, USA
2. ²Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
3. ³University of Minnesota Cancer Center, USA
4. ⁴Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599, USA
5. ⁵Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
6. ⁶Department of Pathology, The Ohio State University, Columbus, OH 43210, USA
7. ⁷IWK Health Centre, Halifax, NS B3J 3G9, USA

Correspondence: Dr JA Ross, Department of Pediatrics, Division of Epidemiology and Clinical Research, University of Minnesota, MMC 422, 420 Delaware St SE, Minneapolis, MN 55455, USA. E-mail: ross@epi.umn.edu

Received 28 June 2004; Revised 22 September 2004; Accepted 22 September 2004; Published online 2 November 2004.

Abstract

Children with Down syndrome (DS) are highly susceptible to acute leukaemia. Given the potential role of infections in the aetiology of leukaemia in children without DS, we investigated whether there was an association between early-life infections and acute leukaemia in children with DS. Maternal infections during pregnancy were also examined. We enrolled 158 incident cases of acute leukaemia in children with DS (97 acute lymphoblastic leukaemia (ALL) and 61 acute myeloid leukaemia (AML)) diagnosed at Children's Oncology Group institutions between 1997 and 2002. DS controls (N=173) were selected from the cases' primary care clinics and frequency matched on age at leukaemia diagnosis. Data were collected on demographics, child's medical history, mother's medical history, and other factors by maternal interview. Analyses were conducted using unconditional logistic regression adjusted for potential confounders. A significant negative association was observed between acute leukaemia and any infection in the first 2 years of life (adjusted odds ratio (OR)=0.55, 95% confidence interval (CI) (0.33–0.92); OR=0.53, 95% CI (0.29–0.97); and OR=0.59, 95% CI (0.28–1.25) for acute leukaemia combined, ALL, and AML respectively). The association between acute leukaemia and maternal infections during pregnancy was in the same direction but not significant. This study offers support for the hypothesis that early-life infections may play a protective role in the aetiology of acute leukaemia in children with DS.