(The information below about FIT testing in primary care is intended for health and care professionals).
What is FIT?
The Quantitative Faecal Immunochemical Test (FIT) is a test to detect hidden or ‘occult’ blood in stool samples. Unlike older faecal occult blood (FOB) tests, FIT uses antibodies that specifically recognise human haemoglobin and so there is no need for patients to undergo dietary restriction prior to using the test. As it is antibody based, FIT is a more sensitive and specific test than the guaiac test, which most GPs would know as the old FOB test. FIT is used in many worldwide screening programmes, because it can detect more cancers, and particularly advanced adenomas (premalignant adenomas). There are fewer false positives and it is a sensitive enough test to assess patients who are at low risk of developing colorectal cancer.
FIT for screening
The national bowel cancer screening programme has now switched from using the guaiac faecal occult blood test (gFOBT) to FIT. The screening test sensitivity has been set at 120 μg/g to ensure colonoscopy services do not get overwhelmed by demand. This is still more sensitive than the current test and will increase the detection of bowel cancers.
Which patients are eligible for FIT symptomatic?
The NICE guideline for suspected cancer 2015 (NG12) recommended that FOB tests should be offered to adults without rectal bleeding who were classed as “low risk, but not no risk” of having colorectal cancer.
These are patients who are: aged 50 years or over with unexplained abdominal pain OR weight loss, or aged under 60 years with either a change in bowel habit OR iron deficiency anaemia.
FIT during COVID
Regional guidance: Lower GI: referral and FIT testing guidelines, suspected cancer pathway
During COVID-19, virtual consultations have become common. For GI symptoms, a face to face consultation in primary care is recommended, where possible, in order to examine for an abdominal or rectal mass. Where examination has not been performed, this must be documented on the referral form.
Before referring patients with suspected cancer to secondary care:
· Ensure the patient is aware that they are on a suspected cancer pathway and wish to be referred for further investigations.
· Ensure it is appropriate to refer the patient for further investigations. All patients must have a documented WHO performance status. Use of the Rockwood Clinical Frailty Score is also strongly recommended.
· Assess and identify whether the patient can undertake a telephone consultation.
For non-FIT pioneer sites
GPs should continue to refer patients according to current NICE NG12 guidelines.
As per NICE NG12 and DG30 guidelines, where colorectal cancer is suspected but the NG12 criteria are not met, FIT testing should be used to help guide the referral decision.
- If the FIT is ≥10, the patient should be referred on a 2ww pathway.
- If the FIT is <10, examine patient to rule out any abdominal or rectal mass, investigate other causes, safety-net and monitor in primary care. Advice and guidance can be sought where a GP continues to have concerns. There is currently no data to support repeating the FIT following a negative FIT result. Referral into alternative local pathways for malignancy of unknown origin (e.g. ‘Vague Symptoms’ Multi-Disciplinary Diagnostics Centre pathway for HWE) could also be considered.
During COVID, FIT testing has additionally been introduced for patients referred on a 2ww pathway - except for those with rectal bleeding, an abdominal or rectal mass, or anal ulceration. These patients should still be referred on the 2ww pathway, regardless of FIT result, as this will solely be used to inform risk stratification and prioritisation in secondary care.
Table 1: summarises which patients should have FIT and when a 2ww referral should be made. All patients with suspected cancer should also have FBC, ferritin and U&E taken.
Table 1: Guide to FIT assessment and referrals by patient presentation
* For these presentations, NICE NG12 says to consider 2ww referral. If patient is 16-40 yrs and IBD is suspected but cancer is not suspected despite the presence of these symptoms/signs, urgently refer to gastroenterology, rather than 2ww pathway (as per BSG IBD guidelines in Figure 1). Advice and guidance prior to referral could be considered to confirm the correct pathway for the patient.
҂Appointment with Specialist Screening Practitioner (SSP) and offer of colonoscopy/CT colonography via Bowel Cancer Screening Programme (BCSP)
For FIT Pioneer sites
Prior to COVID-19, FIT Pioneer sites were trialling the use of FIT testing for symptomatic patients in primary care as part of the 2ww pathway. Within the East of England, Hertfordshire and West Essex(HWE) is a FIT Pioneer site. Their pre-COVID-19 FIT testing protocol is shown in Appendix 1.
During COVID recovery, GPs in HWE are requested to additionally arrange FIT testing for patients with iron deficiency anemia who are being referred on a 2ww pathway. These patients should still be referred on a 2ww pathway, regardless of the FIT result. The FIT result will be used by secondary care for risk stratification and prioritisation.
For all other indications, GPs in HWE should continue to follow existing local protocols for FIT testing and referrals.
All patients with suspected cancer should also have FBC, ferritin and U&E taken.
Please read our East of England Guideline for the Referral and Prioritisation of Patients with Gastrointestinal Symptoms During COVID Recovery we also have a clinical guide for triaging patients with lower gastrointestinal symptoms (specialty guide for patient management during the coronavirus pandemic).