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FIT Test in Colorectal Cancer Screening - Overview

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The fecal immunochemical test (FIT) detects blood in feces. Blood in the stool might signify precancerous polyps or colon cancer; thus, identification is vital.

Medically reviewed by

Dr. Abdul Aziz Khan

Published At May 20, 2024
Reviewed AtMay 20, 2024

What Is a Fecal Immunochemical Test?

The Fecal Immunochemical Test (FIT) searches for undetectable blood residues in the feces. The test detects human blood, which decreases the likelihood that additional blood, which could have originated from ingestion, will be discovered.

What Is Colorectal Cancer?

Colorectal cancer originates in either the colon or the rectum. These malignancies may also be called colorectal cancer, with the specific terminology depending on their origin. Colon cancer and rectal cancer are frequently classified together due to their shared characteristics.

How Does the FIT Test Help in the Diagnosis of Colorectal Cancer?

A FIT test, or fecal immunochemical test, is a diagnostic procedure to detect stool blood. It utilizes antibodies to identify specific proteins in the blood that may indicate the presence of colorectal cancer or other gastrointestinal conditions.

FIT is an acronym for fecal immunochemical test, a screening method for colorectal cancer that detects the presence of hemoglobin, a crucial protein found in red blood cells, in the feces. Colon cancers or polyps may exhibit bleeding from the blood vessels, although the blood may not always be discernible without magnification. A FIT test employs antibodies to identify occult blood, which refers to concealed blood in the feces. A FIT test is one of the two primary forms of fecal occult blood testing.

Colorectal cancer develops slowly, and identifying precancerous polyps or tiny lesions can significantly enhance the prognosis. Colorectal cancer screening procedures, such as a fecal immunochemical test (FIT) and a colonoscopy, enable early disease detection.

What Is the Objective of the FIT Test?

The FIT assesses the hemoglobin concentration, a protein found in red blood cells.

  • To test for hemoglobin, the feces sample is mixed with a liquid. Subsequently, the sample is introduced into a machine or device equipped with antibodies, a class of proteins that selectively attach to hemoglobin. The machine subsequently determines the presence of hemoglobin.

  • The FIT only identifies undamaged hemoglobin, excluding partially digested hemoglobin originating from the upper gastrointestinal tract. It specifically identifies human blood originating from the lower part of the digestive system, including the colon and rectum. In addition, the FIT test is not influenced by the presence of hemoglobin from certain foods, such as red meat, as it only detects human hemoglobin. Medications do not disrupt the test either.

Who Is Considered to Have an Average Risk of Developing Colon Cancer?

Individuals with a moderate risk of colorectal cancer begin routine screening at the age of 45 and continue until the age of 75. Healthcare specialists will assist individuals between the ages of 76 and 85 establish a screening timetable based on previous outcomes, overall health, and projected lifespan. The average risk is the standard risk level considered typical or normal.

  • Without any personal or familial background of colorectal cancer or colorectal polyps and a history of inflammatory bowel disease (IBS), such as Crohn's disease.

  • Without no known or suspected instances of hereditary colorectal cancer syndromes, such as familial adenomatous polyposis or Lynch syndrome, and no previous history of radiation therapy for cancer in the abdomen or pelvic region.

While anyone can develop this form of cancer, several risk factors can increase the likelihood.

  • Individuals with a personal or family history of colorectal cancer or colorectal polyps, those who have irritable bowel syndrome (IBS), and those with genetic colorectal cancer syndromes are at higher risk for developing colorectal cancer.

  • Obesity or being overweight.

  • Lack of regular physical activity.

  • Alcohol consumption.

  • Smoking.

  • Consuming a less healthy diet.

What Are the Advantages of the Test?

The advantages include the following:

  • They are user-friendly.

  • No alterations to dietary or medicinal regimens are required.

  • Drinking liquids or preparing drinks is not allowed.

  • Affordable.

  • Accepted by the majority of insurance providers.

  • Completed in the confines of the residence.

What Are the Disadvantages of Tests?

The disadvantages include the following:

  • Patients may find the test disagreeable to do.

  • Exhibits a significant rate of false positives.

  • Lacks visualization of the colon and rectum.

  • It may fail to detect polyps or cancers with minimal or no bleeding.

  • Tests may yield inaccurate results in hot regions or due to delays in postal services.

  • Requires annual repetition.

  • Insurance coverage for a follow-up colonoscopy following a positive test may be uncertain.

What Is the Significance of FIT Results?

Upon completion of the test, individuals will receive either negative or positive findings. They can also be called "typical" or "atypical."

  • A negative outcome indicates that the test did not identify any presence of blood in the sample. Nevertheless, there are instances where a test could fail to detect the presence of blood or polyps, which are indicative of colorectal cancer. If an individual continues to exhibit symptoms, healthcare providers may request an additional test.

  • A positive outcome indicates the presence of blood in the feces. If a person receives a positive result, a doctor will likely advise them to undergo a colonoscopy. Colonoscopies can identify and decrease the likelihood of mortality caused by colon cancer.

  • An unclear test result may indicate either an incorrect sample collection by the individual or a technical problem encountered during the laboratory testing process. Since healthcare practitioners cannot ascertain whether a test result is negative or positive, an individual must undergo the test again.

What Does the Result of a Positive FIT Test Mean?

A positive FIT test result indicates the presence of blood in the stool, which may suggest the presence of gastrointestinal bleeding or other abnormalities in the digestive system. Obtaining a positive FIT test does not automatically indicate the presence of colorectal cancer. Additional disorders, such as hemorrhoids, benign polyps, and ulcers, can also result in the presence of blood in the stool. Individuals with positive fecal immunochemical test (FIT) results should promptly seek medical attention for further diagnostic examinations, such as a colonoscopy. Several telemedicine companies that market FIT testing provide additional services for individuals to consult a healthcare professional regarding their next actions.


A FIT test is a form of colorectal cancer screening. The test identifies the presence of blood in the feces that may not be discernible to the unaided eye. The detection of blood suggests the necessity of additional screens to determine the underlying cause of the bleeding. Although a positive outcome does not automatically indicate the presence of cancer, identifying and addressing this condition in its early stages typically enhances the prognosis. Individuals may select other kinds of FIT test kits at home. Individuals can conduct these tests at home, typically without requiring a doctor's appointment.

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Dr. Abdul Aziz Khan
Dr. Abdul Aziz Khan

Medical oncology


colorectal cancerfecal immunochemical test (fit)
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