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A Recent Study Doubts the Value of Colonoscopies.

For many middle-aged adults, colonoscopies are a dreaded milestone in life. The promise has been that beyond age 45, you have the highest chance of catching - and possibly avoiding - colorectal cancer if you put up with the uncomfortable and intrusive procedure of having a camera travel the length of your large intestine once every decade. It ranks as the second most frequent cancer-related fatality in the country. In the US, some 15 million colonoscopies are carried out annually.

The advantages of colonoscopies for cancer screening may now be overstated, according to a landmark study.

This study is the first randomized experiment to directly compare colonoscopies to no cancer screening. The study indicated very modest benefits for the population invited to receive the procedure: an 18% lower chance of developing colorectal cancer and no appreciable decrease in the probability of dying from cancer. It appeared in The New England Journal of Medicine on Sunday.

The clinical effectiveness group at the University of Oslo in Norway is led by gastroenterologist Dr. Michael Bretthauer, who conducted the study. Dr. Bretthauer stated he found the outcomes disappointing.

But he noted that as a researcher, he was required to adhere to scientific principles. "I think we ought to accept it," he added. We need to dial back the message a little since we may have oversold it over the past 10 years or so.

According to Dr. William Dahut, chief scientific officer at the American Cancer Society, who was not involved in the study, "I believe it's really hard to assess the utility of a screening test when the majority of people in the screening didn't get it done."

Just 42% of research participants who were asked to obtain a colonoscopy actually did so.

The treatment was found to be more beneficial when the study authors limited the results to the individuals who underwent colonoscopies—roughly 12,000 out of the more than 28,000 who were invited to do so. It slashed the risk of developing colorectal cancer by 31% and the chance of dying from it by 50%.
According to Bretthauer, the genuine advantages of colonoscopy likely fall somewhere in the middle. He stated that he considers about the outcomes of the entire trial, including both those who underwent colonoscopies and those who did not after being invited. He considers the outcomes from the small group of individuals who actually underwent the test to be the greatest advantage that could be anticipated from the process.

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According to his findings, screening colonoscopies are likely to lower a person's risk of developing colorectal cancer by 18% to 31% and their risk of dying by 0% to as much as 50%.

However, even 50%, according to him, is "on the low end of what I believe everyone imagined it would be."

Colonoscopies may cut the chance of dying from colorectal cancer by as much as 68%, according to other studies that have projected bigger benefits.

The Northern-European Initiative on Colon Cancer, or NordICC, study comprised more than 84,000 men and women from Poland, Norway, and Sweden who were 55 to 64 years old. No one had ever had a colonoscopy. The individuals were either observed for the study without being examined or they were randomly invited to have a screening colonoscopy between June 2009 and June 2014.
The group that was asked to receive colonoscopies had an 18% lower risk of colorectal cancers in the ten years following enrolment than the group that wasn't screened. The risk of dying from colorectal cancer was marginally lower overall in the group that was invited to the screening, but that difference was not statistically significant, so it might have been a coincidence.

Before the NordiCC study, observational studies that looked back in time to assess the frequency of colorectal cancer diagnoses in those who underwent colonoscopies with those who did not had been used to gauge the benefits of colonoscopies.
Scientists use randomized trials to blindly divide participants into two groups: those who are assigned to receive an intervention and those who are not since these studies are prone to bias. Then, these studies track both groups throughout time to check for any differences. These studies have been challenging to conduct because colon cancer can grow slowly and may take years to diagnose.

Participation in screening is crucial, according to Dominitz, as to date, significantly more malignancies have been found in the group assigned to stool testing than in the group assigned to receive a colonoscopy.

© 2022 Christian Daniel

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