Compare blood-based colorectal cancer screening options to standard colorectal cancer screening options.

Colonoscopies and more established stool-based tests are more effective at detecting early cancer and precancerous polyps compared to emerging blood-based tests, so their long-term impact is expected to be significantly larger than blood-based tests. According to a recent study published by Ladabaum et al. Annual report of internal medicine. The findings of this study make newly available blood-based tests ideal for patients who forego other colorectal cancer screenings, even though colonoscopies and stool-based tests are It has been found that colorectal cancer mortality rates can increase when many patients who would otherwise have received these tests switch to these blood tests. rise.

background

At current population screening rates, approximately 4% of U.S. adults will be diagnosed with colorectal cancer during their lifetime. Regular screening not only helps identify early cancer and precancerous polyps, but also helps reduce a patient's risk of developing and dying from colorectal cancer. The U.S. Preventive Services Task Force currently recommends that all adults between the ages of 45 and 75 be screened for colorectal cancer.

For decades, screening required either a colonoscopy once every 10 years or a stool-based test every 1 to 3 years. A colonoscopy allows doctors to detect colorectal cancer as well as remove precancerous polyps that can develop into cancer.

“This makes colonoscopy a unique cancer screening method, as it also has cancer prevention potential,” the study's lead author emphasized. Dr. Uri RadabaumProfessor, Department of Gastroenterology, Stanford University. “Anyway, there are a lot of [patients] These are people who aren’t getting tested at all or aren’t getting tested as often as they should,” he pointed out.

Data shows that approximately 33% of U.S. adults in the recommended age range have never been screened for colorectal cancer. As a result, doctors hope they will be screened using new methods.

In 2014, the U.S. Food and Drug Administration (FDA) announced the first multi-targeted stool-based colorectal test that analyzes stool collected by patients at home every one to three years for the presence of small amounts of blood or cancer DNA. Approved the screening test. . In the summer of 2024, the FDA approved a new colorectal cancer screening strategy that detects trace amounts of cancer DNA circulating in a patient's bloodstream. Blood-based tests may sound more appealing than standard invasive colonoscopies, but these first-generation blood-based tests do not properly diagnose precancerous polyps. It is not possible.

“The blood of the first generation…[based] The test is a very interesting development in the colorectal cancer screening paradigm. [However]for now, if [patients are] willing and able to perform a colonoscopy or stool-based test; [they shouldn’t] Turn it into blood-[based] Test it,” Dr. Radbaum warned. “This is a time of great interest in the field of colorectal cancer screening, and the screening paradigm may be changing. [b]Conducting randomized controlled trials to directly compare these new screening tests over time is impractical and would place patients in a difficult position when considering their options. ' he suggested.

Research methods and results

In a recent study, researchers used previously published data on six blood- and stool-based screening tests on the market or in development and standard colonoscopies to examine colorectal endoscopy. We modeled the relative rates and mortality of colorectal cancer in 100,000 average-risk patients using the test. Each screening approach.

Researchers found that of 100,000 patients who undergo a colonoscopy every 10 years, 1,543 will develop colorectal cancer and 672 will die from colorectal cancer. . For stool-based tests taken every 1 to 3 years, the incidence of colorectal cancer ranged from 2,181 to 2,498 per 100,000 patients, and the number of deaths ranged from 904 to 1,025. The new blood-based test, which is recommended to be performed every three years, resulted in 4,310 to 4,365 cases and 1,604 to 1,679 deaths, approximately 2.5% compared to the colonoscopy group. It was twice as expensive. Of those not screened, 7,470 people will develop colorectal cancer and 3,624 will die from colorectal cancer.

Additionally, when researchers looked at the costs associated with each test, they found that colonoscopies and stool-based tests were more cost-effective than blood-based tests.

Researchers found that at a population level, blood-based testing is effective in reducing colorectal cancer mortality if patients are reliably tested every three years and then followed up if they receive a positive result. He pointed out that this would only be possible if the patient agreed to undergo a colonoscopy.

“A blood test is certainly much better than nothing, but if you have a blood test, you're going to worsen outcomes in the population and increase health care costs. [patients] We are switching from colonoscopies to first-generation blood tests,” Dr. Raderbaum said.

They modeled the impact of patient selection on population-wide colorectal cancer incidence and found that most patients continue to be screened with colonoscopy or stool-based testing as a best-case scenario. I discovered. The researchers emphasized that blood-based tests should only be used in patients who do not undergo screening.

conclusion

“We still don't know who will actually use that blood, but[based] test. Will that happen? [patients] People who have not been tested by other methods, [a]And would they be willing to undergo a follow-up colonoscopy if indicated? ” said Dr. Radabaum.

Further research will include real-world data on patient preferences regarding colorectal cancer screening to further refine models of how blood-based tests impact colorectal cancer morbidity and mortality. It may be necessary.

The researchers noted that even if blood-based tests improve, the current results will not apply to future generations of tests. Nevertheless, they hope that patients and physicians will continue to use the most effective screening methods currently available.

“Ideally, as many [patients] “We need all the tests we can to get screened for colorectal cancer, and that will probably mean a combination of tests used across the population,” Dr. Raderbaum concluded. .

Disclosure: Research for this study was funded by the Golindo Family Foundation. For full research author disclosure, please visit: acpjournals.org.