Blood testing is now included in screening recommendations for colon and rectal cancer

The American Cancer Society has updated its colorectal cancer screening guidelines to include new testing options, marking the first time a blood test has been recommended. These updates are designed for adults age 45 and older who are at average risk for colorectal cancer and have either declined or been unable to complete visual exams or stool-based tests.

The new blood-based option is the Shield test, developed by Guardant Health and approved by the US Food and Drug Administration in 2024. The guidelines now include ColoSense, a new FDA-approved test from Geneoscopy, and an upgraded version of Cologuard known as Cologuard Plus.

Bridging the Screening Gap

Medical professionals have noted a rise in colorectal cancer cases among younger populations. However, many individuals skip essential screenings due to the invasive nature of certain exams or a reluctance to collect fecal samples.

Dr. William Dahut, chief scientific officer for the American Cancer Society, noted that providing more options may allow more people to be screened. This increase in participation could lead to earlier cancer detection and a higher number of cured patients.

Did You Know? It is estimated that more than 90% of people who detect colorectal cancer at stages I and II will survive at least the next five years.

The Hierarchy of Screening Options

Despite the introduction of blood tests, colonoscopies remain the gold standard for detection. Performed under anesthesia, this procedure allows doctors to closely examine the colon and rectum for warning signs of disease.

American Cancer Society endorses blood tests as option for colorectal cancer screening

A primary advantage of visual exams is the ability to identify and remove precancerous polyps before they turn into cancer. While stool tests can also detect signs of these polyps, a positive result must be followed by a colonoscopy to provide an opportunity for prevention.

The blood-based Shield test is not currently considered the first choice because it is not as sensitive as other options in detecting precancerous polyps. Researchers emphasize that it should be reserved for those who will not complete preferred screening methods.

Expert Insight: Samantha Carter suggests that these guidelines reflect a pragmatic shift in public health. By acknowledging that “perfect is the enemy of good,” the medical community is prioritizing the broadening of screening capture—especially for vulnerable and younger populations—over the absolute sensitivity of a single test.

Looking Ahead

The introduction of the Shield test may be the start of a broader trend in diagnostic technology. Dr. Scott Kopetz of The University of Texas MD Anderson Cancer Center suggests that more blood-based tests could be on the horizon.

Future developments in this technology may continue to reduce barriers to access. It is likely that subsequent tests will offer improved performance as the technology evolves.

Frequently Asked Questions

Who is eligible for the new blood-based screening recommendation?
The recommendation applies to adults age 45 and older who are at average risk for colorectal cancer and who have not completed or have declined visual exams and stool tests.

Why is a colonoscopy still preferred over a blood test?
Colonoscopies are more sensitive in detecting precancerous polyps and allow doctors to remove them during the procedure, providing a preventative benefit that blood tests do not currently match.

What happens if an at-home stool test returns a positive result?
According to the American Cancer Society, a positive stool test must be followed up with a colonoscopy to allow for further prevention and diagnosis.

How do you feel these new, less invasive testing options might change the way people approach cancer screenings?