In this review results are presented from several population-based epidemiological and immunological studies of children with leukaemia in The Netherlands, who were diagnosed between 1973 and 1982 through a nationwide co-operative group of paediatricians. From 1973 till 1980 annual incidence rates appeared to be 3.1 per 10(5) person-yr. No significant trend was observed in this period. However a preliminary analysis of patients in the 1980-1982 period showed an increase. Mortality rates are decreasing since 1973, as expected. Incidence rates and proportions of different morphological and immunological subtypes reflect the pattern of occurrence in populations with a high standard of living. A relatively high incidence rate of acute lymphocytic leukaemia (ALL) is observed with a peak at the age of 3-5. The proportion of patients with T-cell phenotype among ALL-patients, immunologically typed between 1979 and 1982, appeared to increase with age, while the proportion of common ALL decreased. Statistical analysis of the data of patients with ALL in the Western part of the country including areas with nuclear plants, gave no indication for the presence of clustering. Subclassification of childhood leukaemia (CL), notably ALL, may be necessary for obtaining more specific etiologic clues. In view of the incidence of CL and ALL large scale, immunological and epidemiological investigations of CL, and the related non-Hodgkin's lymphomas, preferably population-based, are necessary.
Acute Disease Adolescent