Bowel Screening Test

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Graphic of FIT kit

More information for patients:

If you are looking for more information on your FIT result or have any questions, please make an appointment with your GP or you can speak to one of our Nurses on 0808 800 4040

Bowel cancer screening reduces bowel cancer mortality. Since bowel cancer screening began in the UK, it has made use of a certain type of faecal occult blood test - a guaiac-based test (gFOBT). Now, the guaiac test is being replaced by a Faecal Immunochemical Test (FIT) test.

Here you can find information on the new test, it’s implementation and how this will affect healthcare professionals, people invited for screening, and patients.

The Faecal Immunochemical Test (FIT) uses antibodies that specifically recognise human haemoglobin (Hb). It means that a FIT result is not influenced by the presence of other blood in stools, such as that ingested through diet, compared to the guaiac Faecal Occult Blood Test (gFOBT), therefore reducing the chance of false positive results.

It is used to detect and can quantify the amount of human blood in a single stool sample. A positive FIT result suggests that there may be bleeding within the gastrointestinal tract that requires further investigation. Those with a positive result are then invited for further testing, normally colonoscopy.

The bowel cancer screening programme previously used the Faecal Immunochemical Test (FIT). It is intended for people without any signs or symptoms of bowel cancer.

In Scotland, FIT replaced gFOBT as the test for bowel screening in November 2017.

In England, the implementation of FIT began in June 2019.

In Wales, FIT , FIT replaced gFOBT from September 2019.

In Northern Ireland the implementation of FIT screening began in January 2021.

FIT measures micrograms of human haemoglobin per gram of faeces. The definition of a positive or negative result can be changed by altering the numerical FIT threshold. As a general statement, the lower the threshold or cut-off, the more sensitive the test will be and the more cases of cancer and adenoma that will be detected and ultimately deaths from bowel cancer averted.

In Scotland, FIT was introduced with a cut-off of 80μg/g, which has a higher detection rate for advanced adenomas but a comparable cancer detection rate to gFOBT screening.

In England, FIT has been introduced with a cut-off of 120 μg/g. However, to optimise FIT, there are plans to reduce the sensitivity threshold.

In Wales and Northern Ireland, FIT has been introduced with a threshold of 150μg/g.

As with gFOBT bowel screening, GPs will be notified as to whether a person has participated in the bowel cancer screening programme and if so, whether they had a positive or negative result. GPs will not be given the numerical value of the FIT result.

Safety netting patients

  • Even in patients with a negative FIT screening result, it’s important that GPs continue to be alert to the possibility of bowel cancer, as some cancers may still be missed.
  • GPs should also remind people to be aware of key signs and symptoms of bowel cancer, and to seek medical advice if they notice anything new or unusual, even if they’ve recently taken part in bowel screening.

The use of FIT in bowel cancer screening in the UK has indicated improved participation.

We are starting to see an increase in bowel screening uptake as a result of FIT in England Uptake at 67.5% in Q2 (Jul-Sept 2019) [1].

Uptake of bowel screening in Scotland has increased from 56.2% to 64.1% for comparable 18-month periods before and after introduction of FIT [2].  The increase in uptake after the introduction of FIT was greatest among people from more deprived areas.



While it is anticipated that FIT will make a positive contribution to bowel screening uptake, we’re still expecting it to fall short of that seen in other cancer screening programmes, and inequalities may persist.  FIT will be easier for people to complete because it requires only one stool sample, but we expect patients will still experience barriers to participation that the support of their GP and wider practice team could help them overcome.

Research shows that primary care interventions can significantly increase uptake in bowel screening. The CRUK Primary Care Good Practice Guides offer practical advice to support primary care, or GPs and wider practice team to endorse bowel cancer screening.

Bowel cancer screening has harms as well as benefits, so it’s important to assist patients in making an informed decision about whether to take part. Some harms your patients should be aware of include false positives and negatives, over-reassurance following a normal result and the risks associated with follow-up colonoscopy.

GP Practices can help patients make an informed decision about participating in bowel screening:

  • Ensure patient address details are up to date so that everyone gets their invitations and bowel screening kits.
  • Talk to eligible patients about the bowel cancer screening test opportunistically during consultations.
  • Encourage patients to read the information that comes with their kit so that they can understand more about the role of screening in detecting bowel cancer early and decide whether to take part.
  • Break down practical barriers by explaining how to do the test by using our infographic (for England, Wales and Scotland). People who have not wanted to take part before may be pleased to hear that the process is simpler with FIT than with the guaiac test.
  • Answer patients’ questions and concerns about bowel cancer screening and their result.
  • Keep an eye on patients who have received positive results and ensure there aren’t any barriers to them taking part in the colonoscopy/further investigations.
  • Remind patients that bowel screening works better if people take part each time they’re invited, even if previous results have been negative.

Join the conversation and follow @CRUKHCPs for news, updates and opinion.


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