The Faecal Occult Blood Testing Controversy
“Professor Willie Hamilton was involved in drawing up the NICE cancer guidelines which have caused controversy around the use of faecal occult blood testing in the pathway. Both sides of this debate can be read on pages 16 and 17 of the latest copy of the Digest.” Richard Stevens
Here are his views:
The NICE 2015 guidance was considerably different from the 2005 guidance. Firstly, it used only primary care evidence – as the clinical problem of whom to select for investigation is very much a primary care problem. Secondly it was restructured around symptoms, not cancer sites, on the reasonable grounds that patients present with symptoms, not with possible cancers. Thirdly, it was explicit in its rationale for which patients should be selected for urgent investigation, using a risk of 3% to underpin the recommendations. It also allowed lower risk profiles to be tested if it was possible to do so within primary care. Finally, it explicitly allowed GPs to use their clinical wisdom to override the recommendations where there was good reason to do so. With 350,000 new cancer diagnoses annually in the UK, it was utterly unrealistic to capture the nuances of each and every one in a ‘mere’ 176 recommendations.
One recommendation caused concern in the GI community: testing for blood in faeces (by faecal occult blood or by faecal immunochemical testing (we didn’t specify which). The patient group to be offered such testing are those who do not qualify for a colonoscopy, and did not qualify in previous guidance. Thus, more patients are being offered testing, which should reduce emergency admissions and deaths from colorectal cancer.
GPs have largely welcomed the guidance; probably this is because it matched their clinical experience. Indeed, there has been a relentless rise in cancer diagnostic activity between the 2005 and the 2015 guidance, which probably reflects GPs liberalising their own personal thresholds for investigation. Oddly, this means the guideline may have less impact than expected/feared (delete as appropriate) – as much of the change has already happened. Even so, it will be good to get the right patients having the right tests at the right time.
Willie Hamilton, MD, FRCP, FRCGP
Professor of Primary Care Diagnostics, Peninsula College of Medicine and Dentistry
Exeter
You must be a registered user to join the debate. Comments will be moderated before publication:
2 Responses
Leave a Reply
You must be logged in to post a comment.
Testing for FOB is not available for symptomatic patients in Norfolk which I believe is a mistake, especially as the FIT test is more reliable and would be very useful in deciding whether patients presenting with IDA are likely to have a GI blodd loss cause for the anaemia. I have recenty reviewed a paper for the RCGP which sites faecal calprotectin as a good screening tool for the presence of colorectal cancer. Perhaps the combination of FC and FIT would be a good combination in filtering out those patients who should be referred for an urgent FS/colonoscopy or CTVC.
The disadvantages of traditional gFOBT and the many advantages of faecal immunochemical tests for haemoglobin (FIT) have been very well documented, particularly regarding their use in population-based screening programmes. The disadvantages of gFOBT apply equally, or even more so, to use of these tests for the presence of haemoglobin (a better term than occult blood?) in assessment of patients with lower abdominal symptoms.
What is relevant to this current debate is it must be realised that there now exists a mature and ever-growing evidence-base, from well-designed research studies published in peer-reviewed journals, supporting the use of FIT in this clinical setting. A bibliography is documented below. All studies show that FIT, with a low cut-off, have very high clinical sensitivity for colorectal cancer (CRC), so that a positive test result should stimulate rapid referral for colonoscopy. Probably more importantly, FIT in this clinical context has very high negative predictive value for detection of significant colorectal diseases well worth detecting, namely, CRC plus high-risk adenoma plus IBD.
Further, there are recent publications comparing faecal haemoglobin and calprotectin in the assessment of both CRC and IBD and the evidence is rapidly building that calprotectin is a less good test than FIT: just because calprotectin is available and the subject of an existing NICE guideline does not mean that it should be adopted for assessment of patients suspected with CRC. FIT are the test of choice in this clinical setting.
McDonald PJ, et al. Low faecal haemoglobin concentration potentially rules out significant colorectal disease. Colorectal Dis 2013;15:e151-9.
Cubiella J, et al. Diagnostic accuracy of the faecal immunochemical test for colorectal cancer in symptomatic patients: comparison with NICE and SIGN referral criteria. Colorectal Dis 2014;16:O273-82.
Auge JM, et al. Clinical utility of one versus two faecal immunochemical test samples in the detection of advanced colorectal neoplasia in symptomatic patients. Chem Lab Med. 2016:54:125-132.
Rodríguez-Alonso L, et al. An urgent referral strategy for symptomatic patients with suspected colorectal cancer based on a quantitative immunochemical faecal occult blood test. Dig Liver Dis 2015;47:797-804.
Mowat C, et al. Faecal haemoglobin and faecal calprotectin as indicators of bowel disease in patients presenting to primary care with bowel symptoms. Gut Published Online First: 20 August 2015 doi:10.1136/gutjnl-2015-309579.
Godber IM, et al. Use of a faecal immunochemical test for haemoglobin can aid in the investigation of patients with lower abdominal symptoms. Clin Chem Lab Med 2016;54:595-602.
Thomas CL, et al. Can immunochemical tests for faecal haemoglobin and faecal calprotectin be used to risk stratify patients for referral to colonoscopy for suspected colorectal cancer? Annals of Clinical Biochemistry 2016;53 Suppl 1:38-9.