Implementing screening for colorectal cancer

Issues remain about how to investigate those who screen positive

Clinical review p 1249

We now have proof that screening can reduce mortality from colorectal cancer Three randomised trials have shown that screening by faecal occult blood testing every two years has the potential to reduce mortality by up to 20%.1^–3 With expected compliance rates of around 60%, screening of 50-69 year olds would prevent around 1200 deaths from colorectal cancer each year in the United Kingdom. These estimated benefits are similar to those of three yearly mammography screening in preventing breast cancer mortality, with similar costs of around £40m a year. Thus the UK Screening Committee is about to start two pilot studies examining the feasibility of implementing national faecal occult blood screening. As well as issues concerning the faecal occult blood test itself, there is also no consensus about the best method of investigating those who test positive.

Each pilot site comprises 1 million population, with 20% in the target age range 50-69 years. The pilots will examine a single round of two yearly screening. Thus, faecal occult blood tests will be sent to 100 000 people in year 1 and to the remaining 100 000 in year 2. The test requires participants to take a more active role than with other screening tests. They must sample three consecutive stools and repeat the examination, with dietary restriction, if the result is equivocal (expected in 2% of cases). With a compliance rate of 60% and positivity rate of 2%, 1200 people in …