While patients have new screening options for colorectal cancer, including stool and blood-based tests, studies have warned that blood tests are not as effective at detecting and preventing colon cancer.
Two and a half times more colon cancer deaths can be expected to occur in people taking the blood test every three years as recommended, compared to those who undergo colonoscopy once a decade, according to an Oct. 29 report from U.S. News & World Report.
The test was first approved by the FDA in July, based on the agency's approval of a clinical trial involving 8,000 patients in which the test detected colon cancer in more than 83% of people with a colorectal tumor.
The test only detected precancerous polyps in about 13% of patients.
A new study published Oct. 28 determined that death rates for patients undergoing blood tests are much higher than patients undergoing stool tests or traditional colonoscopies.
The estimated case and death rate for every 100,000 people who choose:
Colonoscopy -- 1,543 cases and 672 deaths
Stool tests -- about 2,200 to 2,500 cases and 904 to 1,025 deaths
Blood tests -- about 4,300 cases and 1,600 deaths
No screening -- 7,500 cases and 3,600 deaths
In October, specialists at the Oregon Clinic in Portland warned patients that Shield is not effective at reducing or preventing colon cancer.
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.