Assessing Evidence for Colonoscopy as a Primary Screening Tool
Reid Ness, MD, MPH, Vanderbilt University Medical Center, Nashville, Tennessee, discusses results from and the limitations of the nordICC trial, which assessed the efficacy of using colonoscopy as a primary screening tool.
Transcript:
Hey, my name is Reid Ness, I'm an associate professor of medicine at Vanderbilt University Medical Center and affiliated with the Vanderbilt-Ingram Cancer Center.
The NordICC trial is the only published study that looks at colonoscopy as a primary screening tool. It offered patients that were identified from their national healthcare databases to be either screened or not screened, and the screening that was offered to them was colonoscopy. They're basically contacted one time and invited for colonoscopy, and they could choose to do so or not. If they didn't show up, there wasn't a follow-up and they didn't try to get them to follow up so, the intervention to encourage them for screening was limited, which shows up in the fact that only 42% of the invited patients actually were screened.
When they first published the study and looked at it as the general results, colonoscopy didn't look good, especially for colon cancer prevention, but then when you actually look at the patients who actually had colonoscopy, you saw that it was very effective, that it decreased the rate of colon cancer by about 40% and colon cancer death by 50%, and this was in only 10 years of follow up. Remember that when you do screen for colon cancer, at first, you're going to find some latent cancers there, you're going to find a big bolus there at the beginning and so there's actually an increased rate of cancer when you start to screen a population before it starts to decrease and so the results were, I think, were very remarkable, given that.
Also, another critique was that their endoscopists may not have been the best. There is a measure of quality of colonoscopy called the Adenoma Detection Rate. And the Adenoma Detection Rate for around 30% of their endoscopists was less than the minimally acceptable adenoma detection rate at that time. Interestingly enough, the minimally accepted Adenoma Detection Rate was actually increased last year from 25% to 35%, thus, we're holding people to a higher standard than that study.
We unfortunately don't have a good idea of how colonoscopy would perform in ideal situations, and when you're looking at cancer prevention, remember your timelines are 10 to 20 years, so it's a big deal. There are some good studies now that are going on looking at FIT [fecal immunchemical test] versus colonoscopy that should come to fruition in the next 10 to 15 years, and we should have some data coming out from them in the next 5 years that will help to inform this question
Source:
Bretthauer M, Løberg M, Wieszczy P, et al. Effect of colonoscopy screening on risks of colorectal cancer and related death. N Eng J Med. Published online: October 9, 2022. 10.1056/NEJMoa2208375
