Incidence of acute lymphoblastic leukaemia in white and coloured children in the Western Cape.

UNLABELLED Objectives. To record the age-specific incidence rate (ASIR) for diagnosed acute lymphoblastic leukaemia (ALL) in coloured and white children aged 0 - 12 years in the Western Cape (WC). DESIGN A retrospective population-based study using the 1991 population census to calculate the mean annual childhood population and the ASIR for ALL in the 0 - 4, 5 - 9 and 10 - 12-year age groups in rural and Cape Town metropolitan areas for the period 1983 - 1999. Odds ratios were calculated using EpiInfo 2000. SETTING Registry records of the paediatric cancer units at Tygerberg and Red Cross War Memorial Children's hospitals where all children with ALL in the WC were initially treated. SUBJECTS All white and coloured children aged 0 - 12 years diagnosed as having ALL from 1983 - 1999. OUTCOME MEASURES The ASIR by age and ethnic group in rural and metropolitan patients in the WC. RESULTS The estimated annual childhood population in 1991 was 709 151 with 80.4% coloured and 19.6% white children, of whom 60% were resident in the Cape Town metropolitan area and 40% in the rural area of the WC. Of 246 children with ALL diagnosed in the period 1983 - 1999, 144 were male and 102 female. The ASIR in coloured children aged 0 - 4 years was 17.1/10(6) in the rural and 30.5/10(6) in the metropolitan area, compared with 55.7/10(6) and 56.2/10(6) respectively in white children. In the 5 - 9-year age group the ASIR in coloured children was 10.0/10(6) in the rural and 16.6/10(6) in the metropolitan area compared with 27.6/10(6) and 26.7/10(6) respectively in white children. The 10 - 12-year age group had comparable incidence rates in both populations and geographical areas. Only one case occurred within a 20 km radius of the Koeberg nuclear reactor. CONCLUSIONS White children have an ASIR for ALL comparable to rates of diagnosis in the USA, while only half as many coloured children aged 0 - 9 years were diagnosed in both the rural and metropolitan areas. This contrast may indicate significant underdiagnosis of ALL in coloured children over the period in question. The change in health policy since 1994, which has improved access to primary health care, may improve the rate of diagnosis among coloured and black children.