The changing face of familial colorectal cancer

摘要

Colorectal cancer is predominantly a disease of elderly people in the developed world. The annual incidence of more than 35 000 cases in the United Kingdom means that many people have at least one affected relative. Colorectal cancer in elderly relatives may be due to shared environmental exposure rather than a true genetic predisposition, although the risk of developing colorectal cancer rises with the number of relatives affected. Genetic factors may have a role in up to 30% of cases, but only a small proportion (less than 5%) of colorectal cancers arise in families with strong histories in which tumours develop at a young age (less than 50 years) and represent truly high risk inherited predispositions. Even so, more than 1500 families per year need to be counselled and screened.