17 May 2005
Colorectal cancer is the third most common form of cancer in the UK, and the second most common cause of cancer deaths after lung cancer. Early detection is an important factor in reducing mortality, and it is predicted that deaths from the disease could be reduced by 15% by the introduction of screening programmes. A number of genes associated with colorectal cancer risk have been identified, and the two most common forms of hereditary colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), although individuals with these syndromes account for only around 2-5% of colon cancers. Regular screening is particularly important for families affected by colorectal cancer, including individuals with known genetic predispositions for the disease, and there are also plans to introduce national screening (see the NHS colorectal screening website). However, current procedures for detection such as sigmoidoscopy and colonoscopy are invasive and unpleasant. Faecal occult blood testing (FOB) followed by referral for colonoscopy for individuals with positive results is an alternative screening method, but has a relatively high false-positive rate.
A research letter in The Lancet this month reports an assessment of the use of faecal DNA analysis for suitability as a screening method [M