Childhood cancer in sibs.

Thirty-eight families with cancer in two or more children were identified from records of the Sidney Farber Cancer Center and the Children's Hospital, Boston. Neoplasms developed in one pair of identical twins and in 37 sets of sibs (2 with 4 affected sibs, 4 with 3, and 31 sib-pairs). Predisposition to cancer extended to their parents and other relatives, and subsequently to other sibs who were unaffected at the time of ascertainment of the cancer-prone families. Genetic susceptibility was suggested in individual families by parental consanguinity or by an inherited disorder predisposing to cancer, but in other instances no oncogenic factors were identified. Familial aggregates of childhood provide opportunities for etiologic study and cancer control.