The weakest link

It has been suspected that there is an inherited susceptibility to inflammatory bowel disease (IBD), ulcerative colitis and colorectal cancer. On this basis it would be reasonable to predict that the relatives of patients with IBD would be at increased risk of colorectal cancer. But research published in 27 January Lancet does not support the theory that there may be a single genetic cause for IBD and this malignant disease.

Johan Askling and colleagues from the Karolinska Institute, Sweden, assessed cancer rates among 114,000 first-degree relatives (that is parents, siblings, and offspring) of IBD sufferers. They compared the incidence of cancer among these relatives with rates in the general population. The relatives of patients with Crohn's disease or ulcerative colitis were neither at increased risk of cancer overall, nor at increased risk of colorectal cancer (Lancet 2001, 357:262-266).

Relatives of patients with both IBD and colorectal cancer had, however, an ...