1. ¹Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, 135 Cannon Street, Charleston, SC 29425, USA
2. ²New York State Cancer Registry, Corning Tower, Room 536, Empire State Plaza, Albany, NY 12237, USA
3. ³Epidemiology Program, School of Public Health, Louisiana State University Health Sciences Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112, USA
4. ⁴Department of Epidemiology and Clinical Investigation Sciences, School of Public Health and Information Sciences, University of Louisville, 555 South Floyd Street, Room #4053, Louisville, KY 40202, USA

Correspondence: AS Adelman, E-mail: adelmaas@musc.edu

Received 5 January 2005; Revised 30 March 2005; Accepted 4 April 2005; Published online 10 May 2005.

Abstract

Acute lymphocytic leukaemia (ALL) incidence among children under 5 years of age was examined, utilising data from 24 United States cancer registries. County-based incidence rates among white children were compared across four levels of urbanisation: large and small metropolitan counties, and adjacent and nonadjacent rural counties. In metropolitan areas, the incidence of ALL was lower among blacks (rate ratio (RR)=0.38, confidence interval (CI)=0.33–0.44) and among Asians/Pacific Islanders (RR=0.78, CI=0.63–0.97) than among whites. Among white children, the incidence of ALL decreased across the four strata of urbanisation, from 67 to 62 to 65 to 54 cases per million person-years at-risk (two-sided trend P=0.009), such that rates were significantly lower in the most remote rural counties than in the most populous metropolitan counties (RR=0.80, 95% CI=0.70–0.91).