Sibling risks in cancer: clues to recessive or X-linked genes?

A systematic analysis of cancer risks to offspring and to siblings of cance r cases was carried out based on the nationwide Swedish Family-Cancer Datab ase. For ail 13 cancer sites examined, risks to both offspring and siblings of cases of cancer at the same site were significantly elevated. The relat ive risk to siblings was approximately 2 fold more than the offspring risk far cancers of the prostate, testis, kidney and bladder, suggesting that re cessive or X-linked susceptibility genes may be important for these cancers . Risks to siblings of cases where a parent was also affected were increase d >20 fold over population rates for colorectal, ovarian. prostate and rena l cancer, and for leukaemia, consistent with the effects of rare high-risk susceptibility alleles. (C) 2001 Cancer Research Campaign.