On the 7th June 2016, the Westminster Government approved the recommendation of the UK National Screening Committee (UK NSC) to replace the current test used in the NHS Bowel Cancer Screening Programme (BSCP) in England with a newer test, the Faecal Immunochemical Test for haemoglobin (FIT). The Scottish Government had already announced the change from the traditional guaiac-based faecal occult blood test (gFOBT) to FIT on 18th February 2015. The rationale for these advances have been very well documented, as have the many advantages of FIT over gFOBT.

The easy to use, hygenic faecal specimen collection device used in the FIT test.
The easy to use, hygienic faecal specimen collection device used in the FIT test.

The first is that, in evaluations in both Scotland [1] and England [2], it has been shown that FIT can increase screening uptake considerably, particularly in the “hard to reach” groups such as younger people, men and the more deprived. This is a great leap forward because screening has a vital role to play in detecting bowel cancer early, when it is more treatable and the chance of survival are high. Increased uptake is really needed, particularly in these groups. However, the downside is that increased uptake means that more people will be referred for colonoscopy.

The second is that FIT are better in detecting bowel cancer and advanced adenoma, which are sometimes precursors of cancer. But, this depends on the faecal haemoglobin cut-off used as the criterion for positivity and subsequent referral for colonoscopy. Indeed, if the cut-off is chosen to give a low positivity as for the current screening programmes in the UK, the clinical outcomes are unfortunately little better than with the current gFOBT [2, 3] . In addition, recent research has shown that the proportion of cancers diagnosed that are interval cancers, that is, cancers occurring in the two years following a negative screening test result, is the same for FIT at high cut-off, as for gFOBT [4] . So, to better reap the benefits of FIT in screening, a low cut-off is required. This leads to higher positivity and, in consequence, an increased demand for colonoscopy.

The traditional gFOBT test requires three samples as opposed to one
The traditional gFOBT test requires three samples as opposed to one

Much has been written about the lack of adequate colonoscopy resources in the UK. Efforts are being made by governments to increase endoscopy capacity. But, some of these are expensive and will take time.  The current crisis in colonoscopy needs tackled with more than one strategy. As discussed in this blog previously – FIT can be used in assessment of patients presenting in primary care with symptoms suggestive of bowel cancer, as well as in screening. FIT do have high sensitivity for cancer detection. More importantly, perhaps, a negative FIT result gives considerable reassurance that significant colorectal disease is absent. Thus, application of FIT would reduce the demand for colonoscopy for symptomatic patients, potentially freeing up the much needed resource for investigation of participants in screening programmes who have a positive FIT result. FIT, if used in more than one clinical setting, could beneficially alter the spectrum of individuals referred for colonoscopy to those who would benefit most.

– Professor Callum G Fraser, Centre for Research into Cancer Prevention and Screening, University of Dundee


References

  1. Digby J, et al. J Med Screen 2013;20:80-5.
  2. Moss S, et al. Gut 2016 Jun 7. pii: gutjnl-2015-310691.
  3. Steele RJC, et al. United European Gastroenterol J 2013;1:198-205.
  4. Digby J, et al. J Med Screen 2015 Nov 19. pii: 0969141315609634.
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