In July, the FDA approved a new screening test for colorectal cancer that only requires a sample of blood.
While the new Shield test was able to detect 83% of colorectal cancers in studies, it only identified 13% of dangerous polyps, whereas colonoscopies find approximately 95% of these polyps.
Now, specialists at the Oregon Clinic in Portland are arguing that Shield is not effective at reducing or preventing colon cancer.
Shield can detect late-stage colon cancer. However, at that point, the disease may either be incurable or require chemotherapy or surgery to remove part of the colon, according to an Oct. 10 report from CBS affiliate KOIN.
The Oregon Clinic, as well as the American Cancer Society, reiterated that the colonoscopy is the gold standard in colon cancer screening and prevention.
While some medical groups are warning the public about Shield's limitations, other physicians remain hopeful that it will increase screening rates for patients who otherwise would not get screened for colon cancer at all.
"I am very excited about the new Shield circulating tumor blood test, which screens for colon cancer-related DNA markers in the blood. There are many patients who would prefer blood-based screening instead of a colonoscopy or stool-based testing. The convenience of screening for colorectal cancer with a simple blood draw is pretty amazing," Benjamin Levy III, MD, a gastroenterologist at University of Chicago Medicine, told Becker's.
Colorectal screening among 45- to 49-year-olds has increased threefold since 2021, and the uptick is likely due, in part, to more widespread use of noninvasive colorectal cancer screening methods, including Shield.