During colonoscopy, a physician can visually detect tubular adenomas and remove them at the time of the procedure; waiting until a blood test is “positive” may lead to a scenario where the CRC could have been prevented years beforehand.

It is important to have a detailed discussion with the patient regarding the risks and benefits of these options prior to testing. Physicians should confirm that patients are willing to undergo a colonoscopy if test results return positive. The concept of a false-positive should also be thoroughly explained.

Continue Reading

It is important to note to the patient, however, that if the septin-9 test is positive, a colonoscopy is required. If the patient is adamantly against a colonoscopy regardless of the septin-9 result, the test is not worthwhile.

Related Articles

The septin-9 blood test is non-invasive and does not require extended time away from work or anesthesia. Though the septin-9 test is commercially available and approved by the US Food and Drug Administration, it is not yet recommended in any prominent CRC screening guideline.

Finding a more specific and sensitive blood test for CRC detection and/or pre-cancerous lesions will likely be an important future focus of research in both gastroenterology and oncology.


  1. Torre LA, Bray F, Siegel RL, Ferlay J, Lortet-Tieulent J, Jemal A. Global cancer statistics, 2012. CA Cancer J Clin. 2015;65(2):87.
  2. Siegel RL, Miller KD, Jemal A. Cancer statistics, 2017. CA Cancer J Clin. 2017;67(1):7.
  3. Ahlquist DA, Taylor WR, Mahoney DW, et al. The stool DNA test is more accurate than the plasma septin 9 test in detecting colorectal neoplasia. Clin Gastroenterol Hep. 2012;10(3):272.
  4. Jin P, Kang Q, Wang X, et al. Performance of a second generation methylated SEPT9 test in detecting colorectal neoplasm. J Gastroenterol Hepatol. 2015;30(5):830-3.
  5. Grutzmann R, Molnar B, Pilarsky C, et al. Sensitive detection of colorectal cancer in peripheral blood by septin 9 DNA methylation assay. PLoS One. 2008;3:e3759.
  6. deVos T, Tetzner R, Model F, et al. Circulating methylated SEPT9 DNA in plasma is a biomarker for colorectal cancer. Clin Chem. 2009;55:1337-46.