The American Cancer Society has updated its colorectal cancer screening guidelines, introducing a blood test for the first time. This move aims to make screening easier for adults who decline more invasive options, such as colonoscopies or stool tests.
Colonoscopy remains the gold standard for detecting colorectal cancer, which can develop in the colon or rectum. It allows doctors to closely examine these areas for warning signs. However, many people avoid screening due to the invasiveness or discomfort associated with these methods. As colorectal cancer rates have risen among younger adults, finding ways to encourage screenings is crucial.
The newly recommended blood test is called the Shield test, developed by Guardant Health. Approved by the FDA in 2024, this test is now a viable option for adults aged 45 and older who are at average risk but haven’t completed other tests.
There are also advancements in stool-based tests, such as the improved Cologuard Plus and the new ColoSense, allowing people to collect samples at home.
Experts, including Dr. William Dahut from the American Cancer Society, emphasize that blood-based tests are not the first choice due to their lower sensitivity in detecting precancerous polyps. However, they believe having more options will encourage people to get screened. “We hope more choices will lead to earlier cancer detection,” he said.
Experts suggest that early screening can greatly increase survival rates. For instance, over 90% of people diagnosed with colorectal cancer at stages I and II survive for at least five years. When cancer is detected later, treatment can become more complicated.
Dr. Ursina Teitelbaum from the University of Pennsylvania also supports the new guidelines. She notes that while blood tests are not perfect, they address the need for diverse screening options, especially for younger populations reluctant to undergo traditional screening.
Meanwhile, it’s estimated that around one in three adults eligible for screening have not yet been tested. Colorectal cancer has become the leading cause of cancer deaths among U.S. adults under 50. According to Guardant Health, blood tests can significantly increase screening rates, with more than 90% of people completing a blood test compared to only 28% to 71% of those who undergo colonoscopy or stool tests.
The Shield test identifies tumor DNA in the blood, with about 83% sensitivity for colorectal cancer detection. However, it’s less effective for stage I cancers. Dr. Scott Kopetz from MD Anderson Cancer Center points out that while this test is a good start, ongoing research aims to improve future blood tests for screening younger populations.
For now, the American Cancer Society recommends starting screenings at age 45 and continuing until age 75 for those with a life expectancy of over 10 years. Those over 85 are generally discouraged from screening due to the risks involved. The organization continues to evaluate its recommendations, considering data that may suggest an earlier screening age.
