ASSOCIATIONS BETWEEN CONGENITAL-MALFORMATIONS AND CHILDHOOD-CANCER - A REGISTER-BASED CASE-CONTROL STUDY

This report describes a population-based case-control study that aimed to assess and quantify the risk of children with congenital malformat ions developing cancer. Three sources of data were used: the Victorian Cancer Register, the Victorian Perinatal Data Register (VPDR) and the Victorian Congenital Malformations/Birth Defects Register. Cases incl uded all Victorian children born between 1984 and 1993 who developed c ancer. Four controls per case, matched on birth date, were randomly se lected from the VPDR, Record linkage between registers provided malfor mation data. A matched case-control analysis was undertaken. Of the 63 2 cancer cases, 570 (90.2%) were linked to the VPDR. The congenital ma lformation prevalence in children with cancer was 9.6% compared with 2 .50/b in the controls [odds ratio (OR) 4.5, 95% CI 3.1-6.7]. A strong association was found with chromosomal defects (OR=16.7, 95% CI 6.1-45 .3), in particular Down's syndrome (OR=27.1, 95% CI 6.0-122). Most oth er birth defect groups were also associated with increased cancer risk . The increased risk of leukaemia in children with Down's syndrome was confirmed, and children with central nervous system (CNS) defects wer e found to be at increased risk of CNS tumours. The report confirms th at children with congenital malformations have increased risks of vari ous malignancies. These findings may provide clues to the underlying a etiology of childhood cancer, as congenital malformations are felt to be a marker of exposures or processes which may increase cancer risk. The usefulness of record linkage between accurate population-based reg isters in the epidemiological study of disease has also been reinforce d.