Colonoscopy, stool-based screening outperforms blood test for colorectal cancer detection

Key takeaways:

• Among all the CRC screening methods, CRC incidence and mortality rates were highest among those who received blood-based tests.
• Blood-based tests were also more costly vs. their alternatives.

Both colonoscopies and stool-based tests for colorectal cancer screening may be more efficient and cost-effective compared with blood-based tests, study findings published in Annals of Internal Medicine showed.

However, a combination of all the tests is likely needed to boost screening adherence, a researcher noted.

“The first generation of blood tests are a really exciting development in the colorectal cancer screening paradigm,” Uri Ladabaum, MD, a professor of gastroenterology at Stanford Medicine, said in a press release. “But for now, if you’re willing and able to do a colonoscopy or stool-based test, don’t switch to a blood test.”

According to the American Cancer Society, deaths from colorectal cancer (CRC) in the United States this year are expected to decline but are still estimated to reach over 53,000.

Meanwhile, colonoscopies remain the “gold-standard” in CRC screening, but stool-based and cell-free DNA blood-based tests could reshape the screening landscape, the researchers suggested.

In the study, Ladabaum and colleagues analyzed the data of colonoscopies and several blood- and stool-based tests to determine the relative rate of CRC incidence and mortality per 100,000 people who received each screening method or no screening.

They found that for every 100,000 people who receive a colonoscopy every 10 years, 1,543 would develop CRC and 672 would die from the disease.

The cases of CRC ranged from 2,181 to 2,498 for every 100,000 people who received stool-based screening tests — taken every 1 to 3 years depending on the test — whereas deaths ranged from 904 to 1,025.

The cases of CRC among those who received blood-based tests every 3 years ranged from 4,310 to 4,365 per 100,000 people, whereas deaths ranged from 1,604 to 1,679.

Of 100,000 people who received no screening, 7,470 would develop CRC and 3,624 would die from it.

Overall, colonoscopy and fecal immunochemical tests reduced CRC mortality by over 70% and CRC incidence by 75% or more vs. no screening.

In contrast, CRC incidence fell by 68% and mortality by 73% with multi-target DNA stool tests compared with no screening. CRC incidence decreased by 42% and morality by 56% among blood-based test recipients compared with unscreened individuals.

The researchers also reported that the blood-based tests cost $89,000 per quality-adjusted life-years gained vs. no screening, whereas the two other screening methods cost less.

“The blood tests are certainly much better than nothing, but you’ll worsen the population outcomes and raise health care costs if you see people switching from colonoscopies to first-generation blood tests,” Ladabaum explained in the release.

He said that more data on patients’ choices of screening methods are needed to better determine CRC rates.

“It remains to be seen who will really use the blood tests,” he said.

“Will it be people who have never been screened using any other method? And will they be willing to get a follow-up colonoscopy if indicated?”Ladabaum added. “We want as many people as possible to get screened for colorectal cancer, and that’s likely going to mean a combination of different tests being used across the population.”

References:

• Don’t skip colonoscopy for new blood-based colon cancer screening, study concludes. Available at: https://med.stanford.edu/news/all-news/2024/10/colon-cancer-screening.html. Published Oct. 28, 2024. Accessed Nov. 7, 2024.
• Key statistics for colorectal cancer. Available at: https://www.cancer.org/cancer/types/colon-rectal-cancer/about/key-statistics.html. Accessed Oct. 29, 2024.
• Ladabaum U, et al. Ann Intern Med. 2024;doi:10.7326/ANNALS-24-00910.