• Posted January 28, 2025

Blood Test Accurately Detects Colon Cancer

An experimental blood test can effectively and accurately detect colon cancer in middle-aged folks and seniors, a new study says.

The blood test was 81% accurate in detecting colon cancer among people who have the disease, researchers reported at the 2025 American Society of Clinical Oncology Gastrointestinal Cancers Symposium held last week in San Francisco.

It also was 90% accurate in ruling out colon cancer among healthy people, researchers said.

Such a blood test could help boost colon cancer screening rates, lead researcher Dr. Aasma Shaukat, a gastroenterologist with the NYU Grossman School of Medicine, said in a news release.

Currently, about 22% of people eligible for colon cancer screening have never received it, researchers said in background notes. In some states, the percentage is higher than 40%.

The gold-standard screening test for colon cancer is colonoscopy, but patients must undergo unpleasant bowel preparation and then be anesthetized during the procedure.

Fecal blood tests also can be used to screen for colon cancer, but those must be done every year under current guidelines.

“Additional colorectal cancer screening tests that are convenient, safe, and easy to complete are needed,” Shaukat said.

“Until now, we have only had stool-based tests and colonoscopy or sigmoidoscopy. A blood test has the potential for improving colorectal cancer screening rates,” she added.

For the study, researchers tried the experimental blood test on more than 40,000 people ages 45 to 85 at 200 sites across the United States.

Those folks had their blood drawn, then underwent a standard colonoscopy. Researchers compared the results to see how well the blood test stacked up against colonoscopy.

“This blood test represents a new tool in our toolbox of colorectal cancer screening options,” Dr. Pamela Kunz, chief of GI medical oncology at the Yale School of Medicine, said in a news release. 

The results show that such a blood test “may provide a convenient and effective option for colorectal cancer screening in the average-risk U.S. population,” said Kunz, who was not involved in the study.

Researchers said they will continue to study the long-term impact of a blood-based test for colon cancer screening.

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The U.S. Centers for Disease Control and Prevention has more on colon cancer screening.

SOURCE: American Society for Clinical Oncology, news release, Jan. 21, 2025