The F.I.T. test (Fecal Immunochemical Test) is a modern, uncomplicated and non-invasive test that is used for the early detection of colorectal cancer. The test checks a stool sample for hidden (so-called occult) blood, which is not visible to the naked eye.
Occult blood in the stool can be an indication of polyps, precancerous stages or existing tumors in the bowel.
How does the F.I.T. test work?
In an F.I.T. test, a small amount of stool is taken from a stool sample and inserted into an appropriate stool container, which is then delivered or sent directly to a laboratory.
The sample is then examined in the laboratory for traces of human hemoglobin using antibodies that react specifically to human blood. Hemoglobin is the main component (approx. 90%) of red blood cells (erythrocytes).
The use of specific antibodies also makes the F.I.T. test more sensitive and specific than older test methods, which is the main difference.
What are the results of the F.I.T. test?
- Negative: No blood was found in the stool.
- Positive: Blood was detected in the stool.
What do the results tell us and how should we react to them?
A positive result, i.e. the detection of blood in the stool, requires an endoscopic clarification by means of a colonoscopy, unless a complete colonoscopy has been carried out within the last few years, as only an endoscopy can rule out a possible colon cancer or precursors of colon cancer (so-called polyps or adenomas).
However, a positive result does not necessarily mean that cancer is present. Often inflammatory bowel diseases or harmless causes such as hemorrhoids can also cause bleeding.
A negative result means that no blood was detected in the stool and the pre-test probability of a possible bowel cancer is lower.
Does an F.I.T. test replace endoscopic colon cancer screening by means of colonoscopy?
An F.I.T. test cannot replace endoscopic colon cancer screening by means of colonoscopy, but it is an important complementary tool in the early detection of colon cancer. It is non-invasive, easy to perform and therefore much less invasive than a colonoscopy.
However, the F.I.T. test can only detect blood, but not polyps or tumors that do not yet secrete blood. This means that a negative result in the F.I.T. test does not completely rule out bowel cancer.
Colonoscopy is still the gold standard, as it allows visual inspection and removal of polyps at the same time.
When is it recommended to carry out an F.I.T. test?
- The F.I.T. test is usually recommended every 1-2 years from the age of 45 as part of colorectal cancer screening.
- People with an increased risk (e.g. family history, i.e. first-degree relatives with colorectal cancer) can also take the test at a younger age.
Conclusion
The F.I.T. test is a practical, non-invasive option for the early detection of colorectal cancer, but does not replace a colonoscopy. Regular colonoscopy is the preferred method, especially for people with an increased risk (e.g. family history).
