The American Cancer Society (ACS) recently reviewed several of the immunoassay FOBTs – or iFOBTs – that have been approved by the FDA and are now available. The ACS determined that there was enough evidence from clinical studies to add a statement to their Recommendations for Screening and Surveillance for the Early Detection of Adenomatous Polyps and Colorectal Cancer that reads “in comparison with guaiac-based tests for the detection of occult blood, immunochemical tests are more patient-friendly, and are likely to be equal or better in sensitivity and specificity.”

Fecal occult blood testing is performed to detect gastrointestinal bleeding and is a useful, non-invasive screen for the early signs of colorectal cancer, which is the third most frequently diagnosed cancer in the U.S. and the second leading cause of cancer death, according to the ACS. FOBT is routinely ordered and is recommended once a year for men and women over the age of 50, or more frequently (and starting earlier) for those with a family history of this type of cancer. The most common method of FOBT is the guaiac smear test (gFOBT), in which the patient must collect several stool samples and then smear test cards with a small amount of the stool.

With iFOBT, a special brush is used to capture a water sample from within the toilet bowl – it is not necessary to handle the stool. Unlike gFOBT, immunochemical tests will not react with non-human hemoglobin (a component of red blood cells), vitamins, medications, or peroxidase found in some foods that can lead to false positive test results. Consequently, iFOBT requires less patient preparation prior to the test – the patient no longer needs to abstain from certain foods (for example, red meat) and medications (such as aspirin).

Despite these advantages, there are some concerns with iFOBT. Many doctors would like to see more clinical testing, especially among those of average rather than high risk for colorectal cancer. In addition, it is more expensive than the guaiac smear method. However, the Centers for Medicare & Medicaid Services recently announced plans to cover annual screening using iFOBT for Medicare beneficiaries 50 years of age and older. Other health insurance companies are considering or have already decided to cover this test as a substitute for gFOBT. Also of concern is the increased sensitivity of the test. It can detect small amounts of blood that may not actually be indicative of cancer, but which can lead to further but unnecessary diagnostic procedures. Currently available data support this trade-off in order to encourage more people to be screened so that more cancers can be detected and treated.

While it remains to be seen how popular this new method will become among physicians, it is clearly being noticed. Proponents of iFOBT hope that people will find it very user-friendly, which will lead to increased numbers being screened and a reduction in morbidity and mortality from colorectal cancer – a treatable condition if it is detected early enough.