Colonoscopy is one of the screening exams for colorectal cancer, one of the most common cancers. And yet, a recently published randomized study concludes that it does not save lives. What is it really ?
Going through a colonoscopy is an unpleasant and dreaded moment for patients. The intervention consists of exploring with a camera the rectum, the small intestine and the large intestine in search of polyps which could become cancerous in the years to come. It is an integral part of the screening strategy for colorectal cancer, one of the most common among men and women over 50.
Until now, no randomized study has concluded that colonoscopy effectively reduces mortality from colorectal cancer, and by extension, that this screening test is risk-free for health and does not increase the risk of mortality. from any cause. A study published in The NEJM, conducted in Norway, Poland and Sweden, tackled this problem head-on. The conclusions go against what was supposed: this test does not reduce mortality due to colon cancer.
Colonoscopy and incidence of colorectal cancer
The study protocol replicates a colorectal cancer screening program. Among the 80,000 participants in the three countries, some are invited to undergo a colonoscopy (28,000 people), of which 42% will actually pass the examination. The incidence of colon cancer and the deaths it causes are monitored over 10 years and compared to 56,000 people who did not receive an invitation and did not have a colonoscopy. The scientists made sure that the latter did not pass one outside of the clinical trial.
At the beginning of the ten years of follow-up, the scientists first observed an increased risk of colorectal cancer in patients asked to be screened – an expected trend since screening reveals the presence of cancer. But after six years of follow-up, the risk of colorectal cancer in people who are not screened becomes greater. In total, the risk of colorectal cancer is 0.98 in screened patients and 1.20 in unscreened people.
No benefit on mortality
The same follow-up was done for the risk of death from colorectal cancer or any other cause. In this case, there is no benefit for the screened patients. After ten years of follow-up, the risk of death linked to colon cancer is 0.28% (72 deaths listed) for people screened by colonoscopy and 0.31% for people not screened. In the screened group, the scientists listed 11.03% of deaths from all causes in the “screened” group and 11.04% in the “unscreened” group. The study therefore shows that colonoscopy has no benefit on mortality due to colorectal cancer.
Colonoscopy is not the only possible screening test to prevent colorectal cancer, there is notably sigmoidoscopy. This less invasive test only observes the rectum, sigmoid colon and left colon, unlike colonoscopy which goes further up the digestive system. Sigmoidoscopy requires fewer medical resources to perform, but it has gradually been replaced by colonoscopy. Yet the scientists note: These results suggest that colonoscopy screening may not be much more effective in reducing the risk of colorectal cancer than sigmoidoscopy. »
In France, screening for colon cancer (a stool analysis and a colonoscopy in the event of an abnormality) is recommended for all people aged 50 to 74 and reimbursed by health insurance.