Cancer in relatives of children with central-nervous-system neoplasms.

We compared the occurrence of cancer in parents, siblings, and offspring of 643 patients who had central-nervous-system tumors in childhood (cases), as recorded in the Connecticut Tumor Registry, with the occurrence in parents, siblings, and offspring of 360 controls selected according to birth certificate and matched for sex, birth date, and birthplace. Overall cancer incidence was comparable in the two groups. However, 11 nervous-system tumors occurred in relatives of cases, whereas none occurred in relatives of controls (P = 0.0005). Nine relatives of cases but no relatives of controls had cancer of the hematopoietic-lymphatic system (P = 0.003). Nine siblings of cases but only one sibling of a control had cancer as children. Medulloblastoma and glioblastoma multiforme were overrepresented in the group of children whose relatives had central-nervous-system tumors. We compared the actual number of cancers of the central nervous system or hematopoietic-lymphatic system in relatives of cases with the number expected on the basis of known incidence rates and found a fivefold excess. We conclude that the occurrence of a brain tumor in a child is a marker for an increased likelihood of central-nervous-system tumors, leukemia, and childhood tumors in the family.