A new blood test accurately screens for colorectal cancer, researchers say

It could become the second to reach the market, and potentially help boost screening rates.

Colon Cancer Screening
An experimental blood test is about 90% accurate in ruling out colorectal cancer in healthy adults, according to a new study. The Food and Drug Administration approved the first blood test for colorectal cancer last year. Blood tests could boost colorectal cancer screening rates because they are easier than invasive colonoscopies, health experts say.
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A second blood test shows promise for the detection of colon cancer, according to a new study.

The first, called Shield, was approved by the Food and Drug Administration in July for people 45 and older who are at average risk for colorectal cancer. It requires a blood draw at a doctor's office.


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Research about a similar – but still experimental – blood test that has been found to effectively and accurately detect colon in middle-aged and older adults was presented last week at the 2025 American Society of Clinical Oncology Gastrointestinal Cancers Symposium in San Francisco. Preliminary findings show the new blood test is similar in accuracy to Shield, but further study is needed, researchers said.

The advent of blood tests for potentially ruling out colorectal cancer in healthy adults and diagnosing it in people with the disease is significant because about 22% of people eligible for colorectal cancer screenings do not get them. In some states, as much as 40% of people eligible do not get screened. Researchers said blood test screening could boost screening rates, because it is easier and does not involve anesthesia and the intense bowel-evacuation preparation of colonoscopies.

Overall, colorectal cancer rates have been declining. But they have been increasing 1% to 2% annually among younger adults since the mid-1990s, according to the most recent report from the American Cancer Society. Colorectal cancer is now the leading cause of cancer death among men under 50 and second among women in the same age range.

Research that has not yet been peer-reviewed shows the newest blood test is more than 80% accurate in detecting colon cancer in people who had the disease. The test is 90% accurate in ruling out cancer in healthy adults, according to the study published Monday in the Journal of Clinical Oncology.

For the study, researchers used the new test on more than 40,000 people receiving colonoscopies at 200 medical sites around the country. The researchers then compared the results of the blood test screening with the colonoscopy outcomes.

"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 gold standard for colorectal screening is still a colonoscopy, which involves about 24-hours of preparation with a specific cocktail of laxatives and fluids to empty the colon and rectum. People receive anesthesia so that a doctor can use a scope with a light to check for and remove pre-cancerous polyps.

Other screening options are getting a fecal test every one to three years, according to recommendations from a health provider.

Stool tests and blood tests are meant to complement colonoscopies. If the results of these tests are abnormal, people should undergo colonoscopies. Any type of screening is better than no screening, according to the American Cancer Society.