National colorectal screening programmes in the UK

As a result of population based randomised trials carried out in Nottingham, England, Funen, Denmark and Minnesota, USA, a demonstration pilot of colorectal cancer screening using guaiac faecal occult blood test (GFOBT) was carried out between 2000 and 2002 in the United Kingdom. As a result of this pilot, national screening programmes based on GFOBT have been rolled out across the entire country. During the introduction of screening in Scotland, a matched cohort study was carried out to compare areas in which screening was available with areas where it had not yet been introduced. This demonstrated a 10% reduction in deaths from colorectal cancer and when adjusted for participation this reduction was 27%. Thus, there is confidence that GFOBT screening programme is fulfilling its aims However, it is clear that approximately 50% of cancers arising in the screened population are interval cancers and there is very little evidence that GFOBT screening can reduce the incidence of colorectal cancer. A randomised trial of one-off flexible sigmoidoscopy was carried out in multiple centres in the UK between 1996 and 1999 and the results were reported in 2010. This demonstrated that a single flexible sigmoidoscopy between the ages of 55 and 65 not only reduced mortality from colorectal cancer but also reduced the incidence, particularly of left-sided cancer. As a result, flexible sigmoidoscopy is being introduced as a primary screening test for everyone aged 55 in England. There is a concern, however, that the age of 55 is too early for optimum detection of adenomas, and there are also logistic problems in providing sufficient endoscopy resource. For this reason a randomised evaluation of flexible sigmoidoscopy was carried out in Scotland in individuals aged 60 who had been exposed biennial GFOBT screening for 10 years. In this group the added value of flexible sigmoidoscopy was less than that seen in the randomised studies. Thus, there is a dilemma in the United Kingdom as to the ideal screening modality, and a decision has now been taken to introduce quantitative faecal immunochemical testing (FIT) as the primary screening test. Current research is aimed at optimising the use of FIT in combination with age and gender, and also investigating the optimal interval for screening based on the faecal haemoglobin concentration.