Improved Fecal Occult Blood Tests (FOBT) called Fecal Immunochemical Tests (FITs), look for human blood in the stool and are more effective at detecting cancers and polyps than the older and more widely used stool screening tests - the guaiac tests (GTs), said James Allison, MD, an adjunct investigator with the Kaiser Permanente Division of Research, UCSF Clinical Professor of Medicine Emeritus and lead author of the study.
Investigators and gastroenterologist clinicians at Kaiser Permanente's Northern California Division of Research compared the performance of FIT and a sensitive GT in 5,841 people with an average risk for colorectal cancer and looked at the tests' ability to detect colorectal cancers and polyps in people with the disease (sensitivity) and the tests' ability to determine which people do not have the disease (specificity).
The FIT had a sensitivity of 81.8 percent for detecting colorectal cancers and a specificity of 96.9 percent. The GT was 64.3 percent sensitive for detecting colorectal cancers and 90.1 percent specific. The higher specificity of the FIT means that there are fewer false positive results and, therefore, fewer interventional procedures need to be performed in patients without disease, said the researchers.
'FIT is an important and a welcome addition to our screening tool kit, especially because according to the National Cancer Institute, colorectal cancer screening rates continue to lag well behind those for other cancers. All recommended screening tests are effective tools for detecting colorectal cancer early, when it is highly curable,' said Allison. 'No screening test is perfect, but any is better than none, and, ultimately, the best screening test is the one the patient actually completes.' FIT is convenient for patients because it is easy to prepare and complete at home and does not involve dietary restriction, explained the researchers.
FIT is more specific than the sensitive GT for detecting cancers and polyps because it detects human blood in the stool. The GT, on the other hand, detects peroxidase activity found in both human and non human blood as well as in many vegetables such as broccoli and horseradish. This can lead to more false positives, explained the researchers.
FIT has other advantages as well, according to the researchers. Some FITs can be developed and interpreted by lab equipment. This innovation allows for management of large numbers of tests in a standardized manner with excellent quality assurance, they explained.