From the Guidelines
Blood tests for colon cancer screening, such as the Septin9 DNA test, are not currently recommended as the primary screening method due to their lower sensitivity and specificity compared to traditional methods like colonoscopy or stool-based tests. The most recent and highest quality study, 1, focuses on stool-based tests, including the high-sensitivity guaiac fecal occult blood test (gFOBT), fecal immunochemical test (FIT), and stool DNA test, which detect blood or DNA biomarkers in the stool. These tests have been shown to be more effective in detecting colorectal cancer and advanced adenomas compared to blood-based tests.
Methods for Colon Cancer Screening
- Stool-based tests:
- High-sensitivity guaiac fecal occult blood test (gFOBT)
- Fecal immunochemical test (FIT)
- Stool DNA test (sDNA-FIT)
- Colonoscopy: allows direct visualization of the colon and removal of precancerous polyps
- Other methods: flexible sigmoidoscopy, double-contrast barium enema (DCBE), and computed tomographic colonography (CTC)
Limitations of Blood-Based Tests
- Lower sensitivity and specificity compared to traditional screening methods
- Higher false positive rates
- May not detect all types of colorectal cancer
Recommendations
The gold standard for colon cancer screening remains colonoscopy, and stool-based tests like FIT or multi-target stool DNA test are also effective alternatives. Blood-based tests may be considered in specific situations where other screening methods are refused or not feasible, but they should not replace proven screening strategies. Most guidelines recommend beginning screening at age 45 for average-risk individuals, as stated in 1. It is essential to discuss the most appropriate screening option with a healthcare provider based on individual risk factors and medical history.
From the Research
Colon Cancer Screening using Blood Tests
There are no specific blood tests mentioned in the provided studies for colon cancer screening using biomarkers (tumor markers). However, the studies discuss various screening methods, including stool-based tests, endoscopic tests, and molecular tests.
Emerging Screening Modalities
- Blood-based screening or "liquid biopsy" is mentioned as an emerging and novel CRC screening modality that is not yet approved for first-line screening in average-risk individuals 2.
- Stool DNA tests are discussed as a noninvasive screening test for colorectal cancer, but the studies conclude that there is no significant advantage of these tests compared to fecal immunochemical tests (FIT) in detecting colorectal cancer or advanced neoplasms 3.
- MicroRNAs (miRNAs) are mentioned as novel promising biomarkers for CRC screening, but reports on these fecal biomarkers are case-control studies, and each of them evaluates single miRNAs or multi-target panels 4.
Current Screening Recommendations
- The US Preventive Services Task Force recommends screening for colorectal cancer starting at age 45 for average-risk individuals, with several screening strategies, including high-sensitivity guaiac fecal occult blood test (HSgFOBT), fecal immunochemical test (FIT), and colonoscopy 2, 5.
- The studies emphasize the importance of informed decision-making about the benefits and limitations of recommended screening options and the need for a programmatic approach to CRC screening to maximize screening participation 2, 5.