PATTERNS OF CHILDHOOD-CANCER AMONG SIBLINGS

The National Registry of Childhood Tumours contains over 51 000 record s of children born in Great Britain who developed cancer under the age of 15 years. Patterns of childhood cancer among families containing m ore than one child with cancer have been studied. A total of 225 'sib pair' families have been ascertained from interviews with parents of a ffected children, from hospital and general practitioner records and f rom manual and computer searches of names and addresses of patients. A number of special groups have been identified, including those with a known genetic aetiology such as retinoblastoma, twins and families wi th three or more affected children. A further 148 families not in any of the above groups contain two children with cancer: in 46 families t he children had tumours of the same type, most commonly leukaemia. Som e of the families are examples of the Li-Fraumeni syndrome; some are a ssociated with other conditions, including Down's syndrome. There is c learly a genetic element in the aetiology of cancer in some families d iscussed here; shared exposure to environmental causes may account For others and some will be simply due to chance.