New test to improve population-based colorectal cancer screening

A new stool test appears to detect colorectal cancer precursors better than the current fecal immunochemical test. This could further reduce the number of new cases of colorectal cancer as well as the number of people who die from it. A study conducted by the Dutch Cancer Institute compared the two tests.

Their results are published in The Lancet Oncology.

Every year around the world, approximately 1.9 million people are diagnosed with colorectal cancer and 935,000 people lose their lives to the disease. If detected early, colorectal cancer is curable. However, by the time symptoms such as weight loss or blood in the stool appear, it is often too late. This is why many countries have implemented population-based screening programs. In the Netherlands, for example, people aged 55 to 75 are encouraged to get tested every two years.

Most population-wide screening programs use the fecal immunochemical test (FIT), a stool test that measures the presence of hemoglobin, a blood protein. Worldwide, colorectal cancer screening programs have been shown to be effective in diagnosing colorectal cancer at early stages and reducing colorectal cancer mortality.

Three proteins

“The current test works well but leaves room for improvement,” says Gerrit Meijer, senior researcher at the Netherlands Cancer Institute. “We want to be able to detect tumors before they become invasive, that is, at the stage of larger precancerous polyps. Treating doctors can then remove these polyps during a colonoscopy, rather than through surgery.”

Meijer and his colleagues at the Netherlands Cancer Institute, UMC Amsterdam and Erasmus MC have been working on a new test for years. This multitargetFIT (mtFIT) test measures hemoglobin and two additional proteins. A previous retrospective study demonstrated promising results.

Cancer precursors

Today, researchers published results from a much larger prospective study that compared mtFIT to current FIT in more than 13,000 participants in the Dutch national population-based screening program. The study was a success.

“The new test makes it possible to detect cancer precursors more effectively,” explains Meijer. “Our results predict that the test can reduce the number of new cases of colorectal cancer and resulting mortality.” For participants, the new test is just as easy to use as the current test.

More really positive results

The new test showed more positive results than the current test. Although this led to more colonoscopies, with the new mtFIT test, doctors found abnormalities in 299 people, compared to 159 people with the current FIT test. This difference mainly concerned people with a high-risk colon cancer precursor (216 versus 114). Meijer says: “The new test detects more, larger polyps without a significant increase in “false positive” results and therefore unnecessary colonoscopies.

The exact number of colorectal cancer cases that could be prevented with this new test depends on how the current FIT test is used in different countries.

Meijer says: “The Dutch screening program applies a relatively high threshold value to consider the FIT test positive, i.e. unfavorable. Here, the new mtFIT test could lead to 21% fewer cases of colorectal cancer and 18% fewer deaths. use a lower FIT cutoff value, these numbers would be lower, but probably at least 5% fewer people would develop colorectal cancer, with at least 4% less mortality. In both scenarios, the new test could be cost-effective.

Implementing mtFIT into existing FIT-based screening programs will be relatively easy because both tests require fundamentally the same screening logistics.

“This is very good news,” says Meijer. The new test cannot yet replace the current population screening test. “The next crucial step is to produce the test on an industrial scale in accordance with European diagnostic testing guidelines. To this end, we founded the company CRCbioscreen, to enable the test to benefit CRC screening participants in the Netherlands and beyond.