Quantitative Faecal Immunochemical Test (qFIT)
Bowel cancer is the fourth most common cancer in the UK but too often colorectal cancer is detected at a late stage making it the second most common cause of cancer death in the UK. Survival rates are greatly improved with early diagnosis. The risk of bowel cancer rises steeply from around the age of 50–54 years.
qFIT is not a test for cancer. qFIT testing uses specific antibodies against human haemoglobin and quantifies the amount of blood in stool without dietary restriction. Sample collection kits are easy to use. Only one sample is required. If blood is detected, the patient will require follow-up tests to determine the reason for the presence of blood in the stool.
qFIT can be used as a primary screening test aimed at individuals without symptoms, or as a test to guide the management of individuals who present with symptoms. The sample collection process is the same for both but the difference between asymptomatic and symptomatic is the threshold for abnormal results.
Results that are < 10 μgHb/g should be considered as negative in both patient groups and colorectal cancer is unlikely. For symptomatic patients the causes of their symptoms should be investigated further.
Results that are above the threshold (dependent on patient category) should be considered ‘positive’, and may warrant further investigation and possible referral, or be managed at the clinician’s discretion in line with patient history and clinical presentation.
- qFIT has the potential to detect twice as many cancers and four times as many advanced polyps than the current test.
- qFIT measures the amount of blood present in stool while laboratory testing to date has only identified presence of blood.
- qFIT is an adjunct to clinical assessment – as a test it has an excellent negative predictive value.
- High faecal Hb results may be found in patients with less significant bowel disease (e.g. haemorrhoids, simple diverticular disease) which means that the PPV is not optimal.