Colonoscopy is a screening test for colorectal cancer, one of the most common types of cancer. However, a recently published randomized study concluded that it does not reduce the risk of mortality associated with this cancer. explanations.
Article last updated on October 11, 2022
Conducting a colonoscopy is an unpleasant and frightening moment for patients. The intervention consists in exploring the camera rectumrectumI’Small intestineSmall intestine the large intestine, which looks for polyps that can turn cancerous in the coming years; 60 to 80% off Colon CancerColon Cancer Follow the detection of a MassMass Abnormality in the intestine. It is an integral part of the strategy detectdetect colorectal cancerIt is most common in men and women over the age of 50, and is recommended Supreme Health Authority.
Until today, nothing randomized studyrandomized study It was not concluded that colonoscopy was effective in decreasing mortality from colorectal cancercolorectal cancerThus, this screening test is safe for health and does not increase the risk of death from any cause. A study was published in NEJMAnd the NordICC . trial, conducted in Norway, Poland and Sweden, addressed this problem head-on. The conclusions contradict what has been assumed: This test does not reduce the risk of dying from colon cancer. This does not mean that you should do without a colonoscopy to screen for colon cancer. As indicated in the results below, it is an effective examination for locating polyps or adenomas cancerouscancerous attached to the colon.
Colonoscopy and colon and rectal cancer
The protocolprotocol From the study repeats the examination program for colorectal cancer. Of the 80,000 participants in the three countries, some were invited to undergo colonoscopy (28,000 people), of whom 42% will already pass the screening. Colon cancer incidence and mortality are followed over 10 years and compared with 56,000 people who did not receive an invitation and did not have a colonoscopy. Scientists made sure that the latter did not pass anyone outsideClinical testClinical test.
At the beginning of ten years of follow-up, scientists noted for the first time an increased risk of colorectal cancer in patients to be screened – a trend expected since screening revealed the presence of cancer. But after six years of follow-up, the risk of developing colorectal cancer increases in people who have not been screened. In total, the risk of developing colorectal cancer is 0.98 in screened patients and 1.20 in non-screened people, that is, an 18% reduction in risk. Colonoscopy can reduce the risk of colorectal cancer. Among the 42% of guests who have already taken the exam, adenomasadenomas Precancerous carcinomas were detected and removed in 30% of them, thus preventing the possible formation of tumortumor later.
There is no benefit to the death rate
The same follow-up was performed for risk of death from colorectal cancer or any other cause. In this case, there is no benefit for the patients under examination. After ten years of follow-up, the risk of colon cancer-related death is 0.28% (72 recorded deaths) for people screened by colonoscopy and 0.31% for people who have not. In the examined group, the scientists recorded 11.03% of deaths from all causes in the “examined” group and 11.04% in the “unexamined” group. So the study shows that colonoscopy has no benefit on mortality from colorectal cancer.
The study suffers from several weaknesses related to its methodology. in the analysis per protocolSince all people eligible to have a colonoscopy are believed to already do so (which is not the case in fact), the scientists observed a 30% reduction in the risk of colorectal cancer and associated mortality. It is a feature that the authors consider underestimated because the calculations cannot be adjusted for all variables due to the large size of the labor force and the differences between the Norwegian, Polish and Swede populations that make up regimentregiment. Analytics per protocol It was also concluded that the calculated benefit of colonoscopy in Norway is greater than in Poland; The absolute risk of colon cancer is higher in Norway than in Poland.
TheAmerican Society of Gastrointestinal Endoscopy (ASGE) has been published. press release In the wake of NordICC Experience that stipulated it : A “by protocol” analysis, which takes into account people who underwent colonoscopy, there is a 50% reduction in mortality. This is consistent with the compelling evidence from case and cohort studies that colonoscopy prevents colorectal cancer and associated mortality. This new study contains many unexplained issues for changing the consensus about the usefulness of colonoscopy. Colonoscopy, with modern endoscopes and trained endoscopy specialists, remains the most effective and efficient method for detecting and preventing colorectal cancer. »
Colonoscopy or not colonoscopy?
Colonoscopy is not the only possible test to screen for Preventing colorectal cancerthere in particular sigmoidoscopysigmoidoscopy. This test is less invasiveinvasive It allows you to observe only the rectum, sigmoid colon and left colon, unlike a colonoscopy that extends up the digestive tract. Sigmoidoscopy requires fewer medical resources to perform, but has gradually been replaced by colonoscopy. However, scientists note, about the results per protocol Provided by, that: “ These findings suggest that colonoscopy may be no more effective in reducing the risk of colorectal cancer than sigmoidoscopy. Despite everything, colonoscopy remains the method of reference. In France, colon cancer screening (stool analysis and colonoscopy if abnormal) is recommended for all people aged 50 to 74 and reimbursed by health insurance.
The message to keep in mind is that colonoscopy remains an effective way to prevent colon cancer and that if your doctor recommends it, there is no reason not to do it. If this test requires fairly significant medical attention, most often sedation and careful preparation for cleaning the bowel, and is not risk-free (bleeding or bowel perforation is the most serious, but least frequent), it makes it possible to identify a cancerous mass before it is too late. too late. This does not prevent scientists from conducting independent scientific studies to estimate the true benefit of this practice. The NordICC تجربة Experience Alone is not enough to change the recommendations, but it may raise a legitimate question.
