GERMAN CASE-CONTROL STUDY ON CHILDHOOD LEUKEMIA - BASIC CONSIDERATIONS, METHODOLOGY AND SUMMARY OF THE RESULTS

In order to explore potential risk factors of childhood leukaemia, a c ase control study was performed including all incident cases from 1992 to 1994. The study was based on the German Childhood Cancer Registry. It was restricted to cases from West Germany and extended retrospecti vely until 1980 for children who were living in regions covered by a p revious incidence study on nuclear installations (21). The study was c onducted in close correspondence with a preceding case control study i n Lower Saxony (13). Results of this study and of others published in the literature were used to define explicit hypotheses for the present study. This paper presents the methodology of the study and gives an overview of some basic results. More detailed analyses of the investig ated potential risk factors will be published elsewhere. The study com prised a total of 2358 cases (leukaemias, lymphomas, selected tumours) and 2588 controls. Response rates were 81% for cases and 67% for cont rols. For leukaemias, the main results regarding maternal factors, pre gnancy, birth, immune system, ionising radiation, parental occupation and environmental factors were as follows: Positive associations were observed between childhood leukaemias and young maternal age at birth, high birth weight, tonsillectomy and use of pesticides. Some results suggest a protective effect for allergies and vaccinations. A negative association was observed with maternal smoking and childhood leukaemi a. No associations were found with frequency of stillbirths, maternal alcohol consumption, parental exposure to benzene and use of wood pres ervatives. X-ray examinations in early childhood and parental radiatio n exposure did not show any consistent associations with leukaemia. Po tential risk factors were not reported more frequently by cases and co ntrols living in 114 communities with increased incidence rates. The s trength of our study lies in the large number of participating familie s and in the population-based approach.