The study followed nearly 85,000 people aged 55 to 64 from Poland, Norway, Sweden and the Netherlands over a 13-year period to assess whether invitations to colonoscopy screening reduce colorectal cancer incidence and mortality.

Participants were randomly assigned either to receive invitations for colonoscopy screening and follow-up or to a control group receiving no intervention. The study began in 2008.

“Our goal was to verify whether being invited to a colonoscopy screening reduces the risk of developing and dying from colon cancer. To assess this and determine the magnitude of the potential risk reduction, the study had to include a sufficiently large group of people and last an appropriate time,” said Professor Michał Kamiński of the National Institute of Oncology, who led the study.

“Thanks to this study, we know what would happen if people did not have a colonoscopy, and what would happen if people were invited and had the test performed,” he added.

Researchers found that among all people invited to screening — regardless of whether they actually underwent colonoscopy — the risk of developing colorectal cancer fell by 20%.

“This is a significant result,” Kamiński said. “If we could prevent 20 percent of this cancer cases in our society, that would be a significant improvement.”

Participation rates, however, remained relatively low. Only about 40% of invited individuals underwent colonoscopy.

“In the group of people who underwent screening, the risk of developing the disease was reduced to approximately 40-50 percent. This is one of the greatest effects that can be expected from preventive measures in oncology,” Kamiński said.

Colonoscopy allows doctors not only to detect cancer but also to identify and remove polyps, which can later develop into cancer.

“A polyp precedes colon cancer by a few to a dozen years. During the screening, we can easily remove them, thus reducing the risk of the disease,” Kamiński said.

He noted that although not all polyps become cancerous, most colorectal cancers begin as polyps.

The study’s findings on mortality differed from researchers’ earlier expectations.

Scientists found no significant difference in colorectal cancer death rates between the screening invitation group and the control group.

“The results of this study are surprising and different from the assumptions we made many years ago when designing the study,” Kamiński said. “But this is not bad news, but rather very good news.”

According to the researchers, advances in cancer treatment over the past two decades have significantly reduced mortality from colorectal cancer across all four countries involved in the study.

Kamiński said modern treatment methods implemented in Poland, Norway, Sweden and the Netherlands likely contributed to similar mortality outcomes despite differences in healthcare systems.

He stressed that early detection still provides major benefits for patients and healthcare systems.

“For the patient, it is important whether they avoid cancer or can undergo less invasive treatment because the disease is detected at an early stage. For the system, there is a difference in costs. A preventive screening is significantly cheaper than cancer treatment, especially in advanced stages of the disease,” Kamiński said.

The professor also criticized the limited organization of colorectal cancer screening in Poland, where preventive colonoscopy is available to eligible adults over 50 but participation remains low.

“There are no invitations, no structure, no organization, and many elements are missing, so we cannot say we have an organized colonoscopy screening programme in Poland,” Kamiński said.

He said responsibility for low participation rates should not be placed solely on the public.

“There are effective and proven methods that significantly increase participation in these types of preventive programmes. In some countries, it reaches 60 percent. And this is something we should strive for,” Kamiński said.

Poland’s colorectal cancer screening programme is available to people aged 50 to 65 who have no symptoms and have not undergone colonoscopy within the previous 10 years. People aged 40 to 49 can also participate if they have a first-degree relative diagnosed with colorectal cancer.

According to National Health Fund data, 238,000 people registered for screening between the fourth quarter of 2022 and the end of October 2025. Colorectal cancer was detected in 2,153 participants, including 942 women and 1,211 men.

Another screening method, the FIT test, which detects hidden blood in stool samples, is also available through Poland’s Moje Zdrowie programme.

Aneta Pawłowska-Krać (PAP)

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