Fecal immunochemical test explained

Fecal Immunochemical Test (FIT) is a diagnostic technique that examines stool samples for traces of non-visible blood, which could potentially indicate conditions including bowel cancer.^[1] Symptoms which could be caused by bowel cancer and suggest a FIT include a change in bowel habit, anaemia, unexplained weight loss, and abdominal pain.^{[2] [3]} By using a random forest classification model, sensitivity can be increased.^[4]

Note: Blood in stools does not always mean the presence of bowel or anal cancer, it could be from other bowel diseases such as ulcerative colitis, Crohn's disease or even hemorrhoids.

A 2022 UK guideline recommends the use of a FIT threshold of fHb ≥10 μg Hb/g to select patients with symptoms for an urgent referral for colorectal cancer investigation.^[5]

Notes and References

1. Web site: Bowel Cancer: Testing for blood in your poo using the FIT test. Cancer Research UK . 6 December 2021.
2. Quintero . Enrique . Castells . Antoni . Bujanda . Luis . Cubiella . Joaquín . Salas . Dolores . Lanas . Ángel . Andreu . Montserrat . Carballo . Fernando . Morillas . Juan Diego . Hernández . Cristina . Jover . Rodrigo . Montalvo . Isabel . Arenas . Juan . Laredo . Eva . Hernández . Vicent . Iglesias . Felipe . Cid . Estela . Zubizarreta . Raquel . Sala . Teresa . Ponce . Marta . Andrés . Mercedes . Teruel . Gloria . Peris . Antonio . Roncales . María-Pilar . Polo-Tomás . Mónica . Bessa . Xavier . Ferrer-Armengou . Olga . Grau . Jaume . Serradesanferm . Anna . Ono . Akiko . Cruzado . José . Pérez-Riquelme . Francisco . Alonso-Abreu . Inmaculada . de la Vega-Prieto . Mariola . Reyes-Melian . Juana Maria . Cacho . Guillermo . Díaz-Tasende . José . Herreros-de-Tejada . Alberto . Poves . Carmen . Santander . Cecilio . González-Navarro . Andrés . 3. Colonoscopy versus Fecal Immunochemical Testing in Colorectal-Cancer Screening . New England Journal of Medicine . Massachusetts Medical Society . 366 . 8 . 23 February 2012 . 0028-4793 . 10.1056/nejmoa1108895 . free. 697–706. 22356323 . 10486/663879 . free .
3. Web site: Fecal immunochemical test (FIT): MedlinePlus Medical Encyclopedia . medlineplus.gov . en.
4. Baxter . Nielson T. . Ruffin . Mack T. . Rogers . Mary A. M. . Schloss . Patrick D. . Microbiota-based model improves the sensitivity of fecal immunochemical test for detecting colonic lesions . Genome Medicine . December 2016 . 8 . 1 . 37 . 10.1186/s13073-016-0290-3. free . 27056827 . 4823848 . 2027.42/134551 . free .
5. Monahan . Kevin J . Davies . Michael M . Abulafi . Muti . Banerjea . Ayan . Nicholson . Brian D . Arasaradnam . Ramesh . Barker . Neil . Benton . Sally . Booth . Richard . Burling . David . Carten . Rachel Victoria . D'Souza . Nigel . East . James Edward . Kleijnen . Jos . Machesney . Michael . Pettman . Maria . Pipe . Jenny . Saker . Lance . Sharp . Linda . Stephenson . James . Steele . Robert JC. 3 . Faecal immunochemical testing (FIT) in patients with signs or symptoms of suspected colorectal cancer (CRC): a joint guideline from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Society of Gastroenterology (BSG) . Gut. 71 . 10 . 12 July 2022 . 0017-5749 . 10.1136/gutjnl-2022-327985. free. 1939–1962. 35820780 . 9484376 . 10044/1/100510 . free .