What is the comparison between Cologuard (Multitarget Stool DNA test) and Fecal Occult Blood Test (FOBT)?

From the Guidelines

Cologuard is generally preferred over Fecal Occult Blood Tests (FOBT) for colorectal cancer screening due to its higher sensitivity, as evidenced by a study published in 2019 1.

Key Points to Consider

• Cologuard is a multi-target stool DNA test that detects both blood and DNA mutations associated with colorectal cancer, offering approximately 92% sensitivity for cancer detection compared to 74% for FIT (a common type of FOBT) 1.
• The recommended screening interval for Cologuard is every 3 years for average-risk individuals aged 45-75, while FOBT tests need to be performed annually or biennially, depending on the type and guidelines 1.
• Both tests are non-invasive alternatives to colonoscopy, but they're less effective at detecting precancerous polyps, particularly smaller ones 1.
• Cologuard has fewer dietary restrictions before testing compared to guaiac-based FOBT, but it is more expensive (though often covered by insurance) and has a higher false-positive rate than FIT 1.

Comparison of Screening Tests

• The American College of Physicians suggests selecting the colorectal cancer screening test with the patient on the basis of a discussion of benefits, harms, costs, availability, frequency, and patient preferences 1.
• Suggested screening tests and intervals are fecal immunochemical testing or high-sensitivity guaiac-based fecal occult blood testing every 2 years, colonoscopy every 10 years, or flexible sigmoidoscopy every 10 years plus fecal immunochemical testing every 2 years 1.
• The effectiveness of colonoscopy has not been evaluated in RCTs, but it is associated with the best sensitivity for adenomas measuring at least 10 mm and has been widely used for CRC screening on the basis of observational and modeling data 1.

Recommendations

• Cologuard is recommended for average-risk individuals aged 45-75 due to its higher sensitivity and fewer dietary restrictions, despite being more expensive and having a higher false-positive rate than FOBT 1.
• If either test returns positive results, a follow-up colonoscopy is required for confirmation and potential polyp removal 1.
• Patient informed decision making and adherence are important factors in selection of a CRC screening test, and discussion should include topics such as suggested frequency, bowel preparation, anesthesia, transportation to and from the examination site, time commitments, and the necessary steps if a test result is positive 1.

From the Research

Comparison of Cologuard and FOBT

• Cologuard is a multi-target stool DNA (mt-sDNA) test, which is one of the recommended screening strategies for colorectal cancer (CRC) by the US Preventive Services Task Force 2.
• FOBT (Fecal Occult Blood Test) is another recommended screening strategy, which detects blood in the stool, a possible sign of CRC.
• A study comparing flexible sigmoidoscopy and FOBT found that both tests reduce CRC mortality, but there is low-quality indirect evidence that screening with either approach reduces CRC deaths more than the other 3.
• The American College of Gastroenterology recommends CRC screening in average-risk individuals, with options including mt-sDNA test (Cologuard), FOBT, and others 4.
• A prospective trial comparing CT colonography, colonoscopy, sigmoidoscopy, and fecal occult blood tests found that Cologuard (mt-sDNA test) was not directly compared, but FOBT had a sensitivity of 20% for advanced colonic neoplasia, while FIT (fecal immunochemical test) had a sensitivity of 32% 5.

Key Differences

• Cologuard is a non-invasive test that detects DNA mutations and blood in the stool, while FOBT only detects blood in the stool.
• Cologuard has a higher sensitivity for detecting advanced adenomas and CRC compared to FOBT, but direct comparison studies are limited.
• The choice between Cologuard and FOBT should be based on individual patient preferences, medical history, and risk factors, as well as the availability and cost of the tests 2, 4.

Test Performance

• The sensitivity and specificity of Cologuard and FOBT vary depending on the study and population being tested.
• A study found that FOBT had a sensitivity of 20% for advanced colonic neoplasia, while another study found that flexible sigmoidoscopy had a sensitivity of 83.3% for advanced adenomas 3, 5.
• Cologuard has been shown to have a higher sensitivity for detecting CRC and advanced adenomas compared to FOBT, but more studies are needed to confirm these findings 2, 4.