qFIT Testing for occult blood in stool
IMPORTANT UPDATES (July 2022):
Please note, from Monday 18th July 2022 only the qFIT picker will be provided (versus a kit). Please send using the clear specimen bags once the green bag stocks are depleted.
qFIT should now be performed in rectal bleeding – it is a measure of ‘colonic health’ and if negative suggests bleeding is from the anal verge, which is reassuring.
The 2-week-wait colorectal cancer referral guidance has changed, please see here
What is qFIT:
- The qFIT test (quantitative faecal immunochemical test) is now widely used in the National Bowel Cancer Screening Programme (NBSCP).
- It is also a good test to identify symptomatic people at higher risk of having a diagnosis of colorectal cancer.
- As qFIT specifically detects human haemoglobin in stools it has a lower false positive rate than guaiac-based FOB testing because it is not influenced by food consumed.
- It is specific for lower GI blood loss.
In primary care, we can use qFIT with reasonable confidence:
- For symptomatic patients who might have a colorectal malignancy, qFIT performs better than PSA for prostate cancer, CA125 for ovarian cancer and CXR for lung cancer.
- It also substantially reduces the number of colonoscopies performed.
Of those with red flag symptoms suggesting colorectal cancer tested with qFIT, 99.4-100% will be detected, and less than 1% will test negative even though they had cancer (false negatives).
- The risk of false negative seems to be more common in patients with IDA and beta-thalassemia trait, so a concurrent FBC can be useful.
- As it is not a perfect test, we need to safety-net and share uncertainty with our patients.
Risk of colorectal cancer (CRC):
- In an asymptomatic patient >50yr old, the risk of CRC is about 1 in 200.
- In a symptomatic patient group, without qFIT testing, the risk of CRC is 3.3%
- Using qFIT as a test in symptomatic patients defines 2 groups:
- qFIT positive, with a risk of CRC of 16%
- qFIT negative group (without IDA or a mass), with a risk that is below the asymptomatic population i.e. <1 in 200
When to use qFIT testing in primary care
As per the Colorectal 2WW referral form, offer qFIT testing to assess for colorectal cancer in adults at any age with:
- Unexplained weight loss and abdominal pain
- Change in bowels for >3 weeks
- Abdominal pain
- Weight loss
- Unexplained rectal bleeding
- Anaemia (other than iron deficiency)
The Non site-specific (NSSCP) 2WW referral form requires a negative qFIT test prior to referral.
The other group of patients we might want to use qFIT in are those with low-but-not-no-risk symptoms. These are patients who do not meet the criteria described above, but who have unexplained symptoms that could be colorectal cancer (see link under resources to DG30).
GPs can still diagnose IBS in adults under 60 without using this test (as per NICE CG61)
Overview of referral pathways based on symptoms and qFIT result
Flow chart - how to interpret qFIT in (high risk) symptomatic patients:
Reference: Suspected cancer guidance 2015 & BSG guidance 2022; version 12.3
Although qFIT tests are reported as positive or negative, it’s important to note that it is a quantitative test and therefore the absolute amount of blood in the stool can be determined.
With this in mind, the cut-off used by the lab varies depending on whether it is being done as a screening test or to test a symptomatic patient:
- When FIT is used for symptomatic patients presenting to primary care a positive result is considered ≥10 mcgHb/gStool.
- When qFIT is used for the asymptomatic screening population (i.e NBCSP) a positive result is ≥120mcgHb/gStool.
Therefore, if a patient presents with symptoms which would normally trigger a qFIT, you should NOT be reassured by a recent negative screening result. A symptom based qFIT should be offered in this instance.
Practicalities of administering the test
- Request qFIT on ICE
- Print 2 labels: label the picker & label the green bag
- Give to the patient, along with the qFIT instruction sheet (available here)
- Once collected, ask patient to drop sample back into GP surgery
Once stocks of green bags are depleted, please print 1 label for the picker ONLY and use clear bags WITHOUT a label.
Red Whale GP Update: Faecal immunochemical testing and colorectal cancer
Suspected cancer: recognition and referral, NICE guideline [NG12], Jan 2021
Quantitative faecal immunochemical tests to guide referral for colorectal cancer in primary care, Diagnostics guidance [DG30], July 2017
Bowel screening, NICE, May 2019
Review date July 2022
Next review date July 2023
GP Sifter Dr Laura Vines
Contributor Ms Melanie Feldman, Colorectal Surgeon
Lorraine Long, Commissioner