Patterns of childhood cancer by ethnic group in Bradford, UK 1974-1997.

The highly urbanised northern English city of Bradford contains a diverse population from different ethnic backgrounds, including a high proportion of south Asians. We aimed to identify the effect of ethnic group on the incidence and temporal trends of childhood cancer in Bradford. Children (0-14 years) from the district of Bradford, who were diagnosed with a malignancy between 1974 and 1997, were selected from a population-based register. Each child was classified as south Asian (Indian, Pakistani and Bangladeshi), or not, based on their full name using 2 computer algorithms and individual inspection. Mid-year population estimates were used to calculate incidence rates and differences were assessed using Poisson regression. The study included 318 children, of whom 81 (25%) were south Asian. The incidence of all cancers in south Asian children (14.9 per 100,000 person years, 95% CI 11.6-18.2) was higher than non-south Asian children (12.0, 10.5-13.5) although not significantly so (P=0.14). Comparisons by diagnostic subgroup showed no major differences apart from significantly higher rates of acute myeloid leukaemia (AML) in south Asian children (1.9 versus 0.7, P=0.02). The age-specific incidence peaks of all childhood cancers and leukaemias were present in south Asian children aged 5-9 years compared with 0-4 years olds in the non-south Asian population. Non-significant increases of 1.4 and 1.5% in the average annual incidence of all cancers were seen for south Asians and non-south Asians respectively, with a significant rise for non-south Asians with leukaemia of 3.0% (P=0.04). Our timely study shows patterns of occurrence of childhood cancer that differ with respect to ethnic group. Differences are particularly apparent in the excess of AML and incidence peak in 5-9 year olds in south Asian children.