CONCORDANCE FOR CHILDHOOD-CANCER IN TWINS

The causes of most childhood cancer remain elusive; some children clea rly have a genetic predisposition, but in the majority the relative co ntributions of environmental and host factors are not established. One approach to this question is through twin concordance studies, but on ly the most common malignancy, acute leukemia, has been studied to dat e, owing to the rarity of other forms of childhood cancer. The aim of the study was to determine the concordance rates for childhood cancer in twins, in order to clarify the importance of constitutional predisp osition for a range of tumor types. Twins with cancer were ascertained through three cooperative clinical trials groups, a cancer-twin regis try, and a large pediatric hospital. Subjects were sent a postal quest ionnaire requesting information on cancer concordance and zygosity. Da ta were obtained on 556 twins with cancer. Three twin pairs, out of 19 7 twin pairs (76 monozygous, MZ, twin pairs), were concordant for leuk emia, giving an MZ case-wise concordance rate (5%) that is substantial ly lower than previously reported. The case-wise MZ concordance for no n-retinoblastoma solid tumors was 2.2%: Two twin pairs were concordant for CNS tumors, one was concordant for neuroblastoma, and two twin pa irs were concordant for cancer but not for the type of cancer. The res ults of the present study, together with previous data from population studies of siblings and offspring, suggest that there is not in gener al a strong constitutional genetic component for childhood cancers oth er than retinoblastoma. (C) 1996 Wiley-Liss, Inc.