Preventive Colonoscopy: A Key Measure Against Colon Cancer

Every March, health organizations emphasize the importance of early detection of colon cancer, highlighting preventive measures such as colonoscopy. This procedure involves a thorough examination of the colon using an endoscope, allowing for the detection and removal of polyps that may develop into cancer.

The efficacy of screening colonoscopy was notably assessed in the Nordic-European Initiative on Colorectal Cancer (NordICC) study. In this research, one group of participants was invited for a one-time colonoscopy, while a control group was not. Over an average follow-up period of ten years, the incidence of new colon cancer cases and related deaths was evaluated in both groups.

Initial findings published in the New England Journal of Medicine in 2022 indicated an 18 percent reduction in colon cancer risk for those invited to undergo a colonoscopy. However, the risk dropped by 31 percent for those who actually participated in the screening. These results sparked discussions regarding the overall effectiveness of colon cancer screening.

Recently, a new analysis conducted by researchers led by Professor Hermann Brenner from the German Cancer Research Center (DKFZ) in Heidelberg revisited the NordICC data. This fresh analysis revealed that the previous evaluation may have underestimated the preventive benefits of the screening. The researchers differentiated between tumors present at the study's inception and those that could be prevented through the removal of polyps. Their findings indicated that among participants who underwent the colonoscopy, 40 percent of colon cancer cases over ten years were detected early, and 34 percent were prevented altogether. Thus, three-quarters of expected cases without screening could either be detected early or avoided entirely.

Co-author Professor Michael Hoffmeister emphasized the significance of recognizing the early detection of tumors through screening as a positive outcome, rather than a failure of prevention. The researchers also suggested that the actual preventive effects might be even greater due to factors such as delayed cancer registrations or diagnostic colonoscopies performed outside of screening programs, which could lead to an underestimation of screening benefits.

The results from this new assessment align with observational studies demonstrating a substantial reduction in risk associated with colonoscopies. For instance, in the United States, the introduction of preventive colonoscopy has led to a nearly 50 percent decrease in colon cancer rates among older adults.

Researchers hope that this new analysis will clarify uncertainties stemming from the original NordICC findings and reinforce efforts toward colon cancer prevention. They also believe that this methodology could serve as a template for future analyses of screening studies that combine early detection and prevention strategies.