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Does Genetic Susceptibility for Bleeding Affect Quantitative Faecal Immunochemical Test (qFIT) Results?

ABSTRACT: Quantitative faecal immunochemical testing (qFIT) is used to test for blood within faeces that cannot always be visible. The presence of blood in the stool has been shown to be a finding where there may be a problem within the large bowel. The test is able to give a numeric value to the blood in the stool and based on this result, further investigations can be planned, or if normal reassurance given. The test is not perfect and minor bowel problems such as haemorrhoids (piles) can give a raised result. However, we have also seen raised results in people who when investigated have a completely normal large bowel. A small degree of ‘physiological’ non-visible bleeding is likely a normal part of life and for the majority this does not lead to a raised qFIT result. It may be the case in people who have a raised qFIT but then go on to have a completely normal colonoscopy (telescope investigation of the large bowel) that there is a genetic predisposition that increases the amount of normal ‘physiological blood’ that they produce. This leads to the test being falsely positive and the person undergoing an unnecessary investigation. This study aims to use saliva to test for known genetic markers that effect blood clotting and can increase how much someone bleeds. By comparing the occurrence of these genetic markers in people with a raised qFIT and normal colonoscopy to those with a normal qFIT and normal colonoscopy, we can test this theory. Should this be the case it will help explain why the test can be raised in normal large bowel and could lead to different levels of positivity being used for different people.

DISEASE(S): Colon Cancer,Colorectal Cancer,Genetic Predisposition To Disease

PROVIDER: 2718871 | ecrin-mdr-crc |

REPOSITORIES: ECRIN MDR

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Project description:Background and study aims Most bowel cancers develop from adenomas, a type of small growth that grows on the bowel wall. Removing adenomas can help to prevent the development of cancer. The NHS now offers screening for bowel cancer to all men and women aged between 60 and 69 years and from 2010, the age range will be extended to 74 years. The screening test, called FOBT, looks for traces of blood in the stool. People who have a positive FOBT are offered colonoscopy, an examination in which an endoscope is used to examine the lining of the bowel for cancers and polyps. Those who have large or multiple adenomas found at colonoscopy are known to have an increased risk of developing more adenomas and possibly bowel cancer. Therefore they are currently offered surveillance colonoscopy at 3 year intervals. There are a number of problems with this approach. Colonoscopy is a costly procedure requiring a skilled doctor, and it carries a small risk of serious complications. It can miss lesions - indeed most advanced lesions (large adenomas or cancers) found at follow-up examinations were present but missed at the previous colonoscopy. Surveillance colonoscopy is also wasteful of resources because significant lesions are found in only about 3% of examinations, so 97% of surveillance colonoscopies will find either nothing or only small harmless adenomas. This is reassuring to the patient but offers no real benefit. Because more adenomas are now being found as a result of the NHS Bowel Cancer Screening Programme (BCSP), the number of surveillance colonoscopies is increasing and threatens to overwhelm available resources. A more cost-effective way of protecting people with higher-risk adenomas is required. We propose that a new type of stool test (faecal immunological test, FIT) could offer effective protection for this higher-risk group at a fraction of the cost. Only patients who had a positive FIT result would need to be offered colonoscopy. This study is designed to estimate the benefit of this approach. Who can participate? People who have taken part in the Bowel Cancer Screening Programme (BCSP) and have been diagnosed with large or multiple adenomas What does the study involve? Participants are offered the FIT at 1, 2 and 3 years. The test is very simple, requiring participants to collect a tiny amount of stool on a probe and return to the laboratory (easier than the FOBT which requires 6 stool samples). Participants who have a positive FIT result are offered a colonoscopy immediately and their next colonoscopy will be three years later. Those who do not test positive to any of the three annual FITs have their colonoscopy at 3 years in the usual way. We compare the total number of bowel lesions found in people who test positive at the 1st, 2nd or 3rd FITs with the number of lesions found at 3-year colonoscopy in those who had a negative FIT result. If most important lesions are found in the group who have positive FIT results, this would suggests that this new approach could provide effective protection and ultimately mean that colonoscopy could be used only in cases with a positive FIT result.

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Does Genetic Susceptibility for Bleeding Affect Quantitative Faecal Immunochemical Test (qFIT) Results?

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