Malignant lymphomas in children in The Netherlands in the period 1973-1985: incidence in relation to leukemia: a report from the Dutch Childhood Leukemia Study Group.

A retrospective study was done of the incidence of non-Hodgkin's lymphoma (NHL) in children in the Netherlands in the period 1973-85 in relation to that of acute lymphoblastic leukemia (ALL). Complete ascertainment of cases was most likely achieved through the network of cooperating pediatricians of the Dutch Childhood Leukemia Study Group (DCLSG). The incidence of NHL remained constant at 0.75 per 10(5) children per year; the boy/girl ratio was 2.5. In +/- 25% of cases the disease was localized at diagnosis. Of children with NHL who were not listed in the DCLSG leukemia register, 19% had greater than or equal to 25% lymphoblasts in the bone marrow at diagnosis, representing an overlap with ALL of +/- 5%. In 1% of the children with NHL an immuno-deficiency disorder preceded the diagnosis. The incidence of Hodgkin's disease (HD) was 0.3 per 10(5) children per year, with some fluctuation over time, the peak being 0.7 in 1983. The boy/girl ratio was 2.7. Age-specific incidence rates, clinical features of NHL and HD, as well as the ALL to NHL ratio corresponded with those in other European countries and for white children in the USA.