American Cancer Society Adds Blood Test to Colorectal Cancer Screening Guidelines

ATLANTA — The American Cancer Society on Wednesday added a blood test to its recommended options for colorectal cancer screening for the first time, a move aimed at reaching the millions of Americans who are not being screened at all.

The updated guidelines continue to call for people at average risk to begin screening at age 45 and to continue through age 75 if they have a life expectancy of at least 10 more years.

A Last Resort, Not a Replacement

The blood test recognized in the guidelines, called Shield and made by California-based Guardant Health, was approved by the Food and Drug Administration in 2024. It works by detecting fragments of DNA shed by cancerous tumors.

The society recommends the test only for people who cannot or will not undergo more effective screening, such as colonoscopy or stool-based tests. Studies have found the test detects about 83% of colorectal cancers, but it is better at finding advanced disease and considerably less effective at catching early cancers and precancerous polyps, which do not release the same DNA fragments. There are not yet data showing whether the test saves lives over the long term.

Dr. William Dahut, the society’s chief scientific officer, told NBC News that about a third of Americans are not up to date on colorectal cancer screening and that adding a new option could dramatically increase the number of people screened. He acknowledged the test would not be as good at detecting precancerous areas or stage 1 cancers but said it was far better than not being screened.

Other Additions

The guidelines also add new stool sample kits and a recently approved at-home test that looks for blood and molecular markers in stool. People who choose colonoscopy should be screened every 10 years, while other tests are repeated every one, three or five years depending on the method, according to ABC News.

More than 20 million eligible Americans remain unscreened, the society said. The guidelines emphasize that the most effective screening test is the one a person is willing to complete.

Rising Cases in Younger Adults

The changes come as colorectal cancer increases among younger adults. According to the society, about 1 in 5 new cases now occurs in people younger than 55, up from about 1 in 10 in the mid-1990s. Colorectal cancer is now the leading cause of cancer death among people under 50.

Cost and Coverage Questions

The recommendation does not require insurers to cover the blood test. Coverage typically follows guidance from the U.S. Preventive Services Task Force, which has not weighed in. The Shield test costs $895 out of pocket.

Dr. Scott Kopetz, a gastrointestinal oncologist at the University of Texas MD Anderson Cancer Center, told NBC News that doctors are generally enthusiastic about expanding options but worry that some patients may choose the blood test because it is quick and easy, rather than a more effective screening. He called it better than nothing but warned that it could erode the quality of screening some patients receive.