Cancers in the first-degree relatives of children with brain tumours.

We used the nationwide Swedish Family-Cancer Database with 2060 childhood brain tumours diagnosed in the period 1958-1996 to analyse the risk of this tumour by parental cancers and in siblings of childhood brain tumour probands. Groups of patients were compared by calculating standardized incidence ratios (SIRs) for brain tumours in offspring. 1.3% of brain tumour patients had a parent with nervous system cancer; SIRs were 2.4 and 1.88 for diagnostic ages < 5 and < 15 years, respectively. The data showed distinct patterns of familial risks for childhood brain tumours, the SIR was 10.26 for brain astrocytoma given a parent with meningioma. Parental colon cancer was associated with offspring ependymoma (SIR 3.70), and parental salivary gland cancers with offspring medulloblastoma (SIR 13.33, but two cases only). SIR for sibling nervous system cancer from childhood brain tumour probands was 3.55 up to age 61.