A large, 10-year randomised trial has found that simply recommending a common screening procedure for colorectal cancer may not be as beneficial for the general public as hoped for. The study found no difference in cancer death rates between healthy middle-aged people who were or weren’t offered a colonoscopy, though those offered a colonoscopy did have a slightly lower risk of diagnosis. The findings don’t necessarily show that routine colonoscopies aren’t worthwhile, but they will throw more fuel onto the ongoing debate over this form of cancer screening.
The research, known as the Nordic-European Initiative on Colorectal Cancer, or NordICC, is a pragmatic, randomised trial, meaning that it was designed to work as closely to real-world conditions as possible. The trial involved men and women aged 55 to 64 with no apparent higher risk of colorectal cancer in Poland, Norway, Sweden, and the Netherlands. In these and other European countries, colonoscopy isn’t recommended widely the way it is in countries like the U.S. These people were randomly assigned to two groups: One group would be invited to participate in a single screening colonoscopy, while the other control group received no invitation or screening.
The researchers were able to track the median 10-year cancer-related outcomes of nearly 85,000 people, with 28,220 in the invited group and 56,365 in the control group. Over the 10-year period, 0.98% of the invited group went on to be diagnosed with colorectal cancer, compared to 1.20% of the usual-care group — a relative risk reduction of 18%. The death rate from colorectal cancer was roughly the same, however, with around 0.3% of people in either group dying from it over the 10-year period. The overall rate of dying from any cause was also similar in both groups (around 11%). The findings were published over the weekend in the New England Journal of Medicine.
Colonoscopies use a long, camera-fitted tube to look for and often remove suspicious growths inside the colon — growths that could become cancerous or already are. Other observational research has suggested that screening older people via colonoscopies can reduce their risk of both colorectal cancer diagnosis and death. But this is the first randomised trial of its kind to examine its potential in a more real-world setting. Upon closer inspection, though, the findings aren’t so clear-cut about the lack of value behind the procedure.
Perhaps the most important caveat of the study is that only 42% of people invited to get a colonoscopy in the trial actually went to get them. And when the researchers looked specifically at these people, they found that these individuals did have significantly lower odds of developing and dying from colorectal cancer — about a 31% lower risk of diagnosis and a 50% lower risk of death. In other words, telling people to get a colonoscopy could very well have a benefit for the population at large, but only if enough people heed the advice and do so.
In an accompanying editorial, outside researchers Jason Dominitz and Douglas Robertson highlighted these above points and other important considerations in interpreting this data.
For instance, the overall risk of cancer climbs as we get older. So it’s possible that the study will eventually show a clearer, positive difference between those invited to a screening and those not invited as time goes on. And as noted earlier, the countries studied in the trial also have not been supportive of recommending routine colonoscopies. But in the U.S., where the screening is recommended for people as early as age 45, about 60% of eligible Americans have gotten a colonoscopy in the past decade. Many European countries are also relatively less diverse in their population compared to the U.S. That’s important because Black Americans are at higher risk of developing this type of cancer, so any possible benefits from colonoscopy might be more substantial for this group and Americans in general.
All that said, many researchers in the field did expect these findings to show a clear population benefit from even attempting to get people screened for a colonoscopy. And this certainly isn’t the first study to suggest that the expected benefits of cancer screening are more complicated than they appear at first glance. Other studies have suggested that less invasive methods, like a stool test, may just be as effective as a colonoscopy at finding colorectal cancer early enough for an average-risk person. Some researchers have argued that even if colonoscopy is the most accurate method of screening, these other tests should be widely recommended instead because people are more likely to actually take them.
In any case, the researchers will keep studying the participants in their trial and plan to publish their findings at the 15-year mark, while other relevant studies are being conducted right this moment. So either way, this won’t be the final word on colonoscopies.
“Additional analyses, including longer follow-up and results from other ongoing comparative effectiveness trials, will help us to fully understand the benefits of this test,” the authors of the accompanying editorial wrote.