FOCUS ON FIT - 2018 2 INTRODUCTION Alpha Laboratories has been at the forefront of faecal testing in the UK for 20 years. This was initially as the market leader for guaiac-based faecal occult blood testing in hospital laboratories. Tender wins for bowel screening in all four UK countries followed this, as each launched its own screening programme, assessing the average risk in asymptomatic populations. Continuing to provide leading edge products, Alpha Laboratories has been awarded the first contract for quantitative FIT as the front line test in the Scottish Bowel Screening Programme. This will employ the Kyowa Medex HM-JACKarc system. England will also be moving to a quantitative FIT method in the NHS Bowel Cancer Screening Programme in the near future. The use of FIT in the assessment of the symptomatic is changing too, as more publications have demonstrated that the use of quantitative FIT as a “rule-out” test has benefits to clinicians, laboratories and patients. This ‘Focus on FIT’ publication summarises some recent progress and current thinking on the application of FIT for symptomatic patients, following the publication of NICE Diagnostic Guidance DG30. NICE DG30 Declares Faecal Immunochemical Testing FIT for Purpose The long awaited NICE Guidance DG30 on “Quantitative faecal immunochemical tests (FIT) to guide referral for colorectal cancer in primary care” was published in July 2017. Release of this document has now helped to address the debate raised by the NG12 cancer referral guidelines published in June 2015. NG12 recommended Faecal Occult Blood Tests (FOBT) as an aid to the two week wait referral pathway for patients with suspected colorectal cancer from primary care, and where a definitive diagnosis was unclear. Controversy with the NG12 guidelines arose due to the use of the terminology of FOBT, since this method had been withdrawn from the patient pathway in the 2005 guidelines. Although a generic terminology, the majority of FOBT technology at that time was primarily guaiac based which was considered to have poor specificity and sensitivity for use in identification of colorectal cancers in symptomatic patients. The new guidance (DG30) focuses on the peer reviewed data for the more sensitive and specific Faecal Immunochemical Test (FIT) technology that is now available. Using the available data, the Diagnostics Advisory Committee has created an economic model for each of the FIT methods under review. The recommendations from the review, are that quantitative FIT should be used in primary care to guide referral for suspected colorectal cancer in people without rectal bleeding, who have unexplained symptoms, but who do not meet the criteria for a suspected cancer pathway referral outlined in the NICE NG12 guideline (see Table 1). NICE concludes that a cut-off of 10 µg Hb/g faeces should be used to define the threshold for ruling out colorectal cancer. However, they acknowledge that using a lower cut-off than 10 µg Hb/g faeces would create disparity between the available methods, and hence have asked that manufacturers of these technologies should provide performance characteristics to prospective laboratories. The guidance also recognises that FIT detects a symptom of colorectal cancer (haemoglobin) that could also be associated with a range of other conditions. Data from studies reporting diagnostic accuracy for multiple target conditions in the same population, suggested that up to 28.9% of people with a false-positive FIT result for colorectal cancer, did have some form of serious bowel pathology, such as inflammatory bowel disease or highrisk adenoma. The guidance concludes that it is plausible that the number of false-positive results that occur when using the tests to rule out colorectal cancer, could be partially offset by detecting other treatable bowel pathology. The guidance suggests that commissioning groups that implement the use of FIT in their patient referral pathway should be auditing their outcomes to include: ■ The number of patients referred under the 2 week wait for suspected cancer pathway ■ The number of patients diagnosed with colorectal cancer ■ The resultant number of colonoscopies and CT colonographies requested Patient group June 2015 NICE NG12 2005 NICE Guideline Aged 50 years and over with unexplained abdominal pain 2WW if +ve FOB No recommendation Aged 50 years and over with unexplained weight loss 2WW if +ve FOB No recommendation Aged under 60 years with changes in bowel habit 2WW if +ve FOB No recommendation Aged under 60 years with iron deficiency anaemia 2WW if +ve FOB 2WW for unexplained iron deficiency anaemia using M/F specific Ref cut off Aged 60 years and over with anaemia even in absence of iron deficiency 2WW if +ve FOB 2WW for cases of iron deficiency anaemia only (as above) Table 1. Criteria for a suspected cancer pathway referral (2WW = two week wait, FOB = Faecal Occult Blood)
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