Is screening colonoscopy effective?

In the NordICC study, based on previous case-control studies, Early colonoscopy was expected to reduce the incidence of colon cancer 50% to 60%, reported Prof. Dr. Hermann Brenner from the Department of Clinical Epidemiology and Aging Research at the German Cancer Research Center (DKFZ) in Heidelberg (1, 2). The data, published in 2022, represents only the first interim analysis over a ten-year period (2). Additional assessment primary endpoints colon cancer incidence and mortality at 15 years and a final analysis at 30 years.

NordICC Study Structure

In the study The randomized trial included 94,959 men and women aged 55 to 64 years from Poland, Norway, Sweden and the Netherlands who had not previously participated in colon cancer screening and who had not yet been diagnosed with colon cancer. Randomized 1:2, some were invited to early screening colonoscopy and others were not. Cancer incidence and mortality were collected using cancer and mortality registries. Primary endpoints were colorectal cancer (CRC) incidence and colorectal cancer-related mortality at 10 and 15 years.

Results of the NordICC study

In an intention-to-treat (ITT) analysis, the incidence of CRC in the colonoscopy group was only 18% lower than in the control group. In a per-protocol (PP)-adjusted analysis of those who did participate in colonoscopy, the incidence of CRC was reduced by 31%. According to the ITT analysis, CRC mortality was not significantly reduced by 10% in the colonoscopy group and 50% in the PP group. Mortality from all causes secondary endpoint The study found no differences between the colonoscopy and control groups. The study found screening colonoscopies to be safe, with no perforations and only 12.7 cases of major bleeding per 10,000 colonoscopies, all of which can be treated on an outpatient basis.

Problems: low participation rate, course too short.

Several factors contributed to the disappointing result, Brenner explained:

• In total, only 42% of the colonoscopy group accepted the invitation for examination, and in Poland only 33% accepted the invitation. However, colonoscopy with polyp removal may only have a potentially protective effect if it is noticed.
• Brenner suspects that the impact of colonoscopy on CRC incidence increases with longer follow-up periods. Initially, it is mainly existing carcinomas that are detected, meaning that in the first six years, the incidence of CRC is higher in the colonoscopy group than in the control group. However, this allows for early diagnosis and detection of carcinomas at early stages. After six years, the incidence of CRC in the colonoscopy group increasingly falls below that in the control group, and this trend may increase with study duration. Brenner is convinced that most cases of the disease can be prevented with colonoscopy, if common cases that are initially detected early are excluded.

Detection of colorectal cancer remains an important challenge

In addition to primary preventive measures such as lifestyle changes, early detection and prevention of colon cancer through colonoscopy is an important goal. Last but not least, due to demographic changes, a significant increase in CRC cases in Germany should be expected, Brenner said. According to private professor Dr. Christian Pox from the St-Joseph-Stift intestinal center in Bremen, this is out of the question, especially since the NordICC study has proven the safety of the measure. In his experience, those who want to get tested vote with their feet: they want a colonoscopy with the ability to remove polyps and adenomas, not a stool test.

Alternatives can improve participation rates

However, for everyone else, less invasive measures represent an important alternative to colonoscopy: in a Dutch study, 73% of those invited to an immunological stool test (iFOBT) accepted the invitation. When invited to sigmoidoscopy, the participation rate was 31%, and for colonoscopy it was 24%. Even if iFOBT detects fewer late-stage adenomas than screening colonoscopy, the higher participation rate ultimately results in the number of late-stage tumors detected being four times higher than those found in endoscopic procedures, Pox emphasized.

Panorama

Controlled studies Ongoing randomized trials comparing screening colonoscopy with stool immunoassay will expand the evidence on the effectiveness of screening colonoscopy, hopes Professor Dr. Frank Colligs from the Department of Internal Medicine at the Helios Clinic in Berlin-Buch. It will also become clear whether new detection methods based on DNA or proteins in feces, blood or urine can be introduced in this country, as in the United States. He believes a risk-based approach makes sense for people under 50. Known risk factors such as being overweight/ obesitycigarette and alcohol consumption, a diet rich in meat, or family history may help identify those among young people who are most likely to benefit from screening colonoscopy.

Source: Gelbe