From the Guidelines
A FIT (Fecal Immunochemical Test) test in stool is a screening method used to detect hidden blood in the stool, which may indicate colorectal cancer or other digestive tract issues, and it is recommended to be performed annually for adults aged 45-75 as part of routine colorectal cancer screening, as supported by the most recent evidence from 1.
Key Points About FIT Testing
- The test works by using antibodies to detect human hemoglobin protein in stool samples, making it more accurate and less likely to produce false positives from dietary sources.
- Unlike older guaiac-based tests, FIT specifically targets human blood.
- To perform the test, you collect a small stool sample at home using a provided kit, then return it to a laboratory for analysis.
- FIT testing is preferred over older methods because it requires no dietary restrictions before testing, needs only one stool sample, and has better sensitivity for detecting advanced adenomas and colorectal cancers.
- If blood is detected in your stool, your doctor will likely recommend follow-up testing such as a colonoscopy to determine the cause, as bleeding could result from various conditions including hemorrhoids, polyps, inflammatory bowel disease, or cancer.
Comparison with Other Screening Methods
- FIT is compared to other screening methods such as guaiac-based fecal occult blood testing (gFOBT), stool DNA testing, flexible sigmoidoscopy, colonoscopy, and computed tomography (CT) colonography, as discussed in 1, 1, and 1.
- The choice of screening method depends on individual risk, personal preference, and access, with FIT being a recommended option for average-risk adults.
Importance of Annual Testing
- Annual testing with FIT is important for early detection of colorectal cancer, as it can detect hidden blood in the stool, which may indicate the presence of cancer or other digestive tract issues, as emphasized in 1.
- Regular screening with FIT can help reduce the risk of colorectal cancer and improve treatment outcomes, as supported by the evidence from 1.
From the Research
Definition of FIT in Stool
- The Fecal Immunochemical Test (FIT) is a tool used for colorectal cancer screening, as stated in 2.
- FIT is applied as a qualitative or quantitative test and has better sensitivity for hemoglobin than older guaiac fecal occult blood tests, according to 2.
Advantages of FIT
- FIT has several advantages, including the ability to screen using only 1 stool sample per cycle, as mentioned in 2.
- Lowering the cut-off concentration of hemoglobin for designation as an abnormal FIT result can increase the detection of advanced neoplasia, as investigated in 3.
Comparison with Other Tests
- New-generation immunochemical FOBTs (iFOBT), such as FIT, have a significantly higher diagnostic performance compared to traditional guaiac-based FOBTs (gFOBT), as found in 4.
- The area under the curve (AUC) for iFOBTs was 0.87, compared to 0.77 for gFOBTs, indicating better performance of iFOBTs, as reported in 4.
Application and Performance
- FIT can be applied at the patient level, and its performance can be tracked at the program level, as outlined in 2.
- The positive predictive values for advanced neoplasia and colorectal cancer (CRC) were 18.9% and 1.7%, respectively, for the lower threshold, as compared to 24.4% and 2.4% for the standard threshold, as found in 3.