Are Colonoscopies Effective?
A study recently published in the New England Journal of Medicine about the effectiveness of colonoscopy is making the news!
This study, the NordICC trial, which was performed in Norway, Poland, and Sweden, claims that it found that colonoscopy is not as effective at preventing colon cancer and death as previously thought. However, there are several issues with the study that may not make it applicable to colonoscopies in the United States:
The Study is Not Representative of Colorectal Cancer Screening in the United States
This study was conducted in Norway, Poland, and Sweden which has a population very different than in the United States and may have different rates of polyps and colon cancer, especially among communities of color.
In the United States, guidelines state that gastroenterologists should be detecting adenomas (pre-cancerous polyps) in at least 25% of screening colonoscopies. This number makes sure that gastroenterologists are performing high-quality exams and finding enough adenomas. A recent study actually found the average adenoma detection rate in the United States is 39%. In contrast, in the NordICC trial, almost 1/3 of the endoscopists had an adenoma detection rate below 25%. This means that the gastroenterologists in the study may have been missing polyps.
Half of the Patients in the “Colonoscopy” Group of the Trial Did Not Have a Colonoscopy
In the NordICC trial, only 42% of people invited to have a colonoscopy actually had a colonoscopy. But even the people who did not go through with a colonoscopy were still included in the “Colonoscopy” group when calculating the results. This likely brought down the calculated effectiveness of colonoscopy.
In the people who did get a colonoscopy, colonoscopy was effective — their risk of colorectal cancer was reduced by 31% and the risk of dying from colorectal cancer was reduced by 50%.
Prior studies have shown that colonoscopy reduces the risk of colorectal cancer by more than 50% and reduces the risk of dying from colorectal cancer by almost 70%.
Colonoscopy is Still the Gold Standard
Colonoscopy remains the only test that screens, detects, and prevents colorectal cancer.
The U.S. Preventative Services Task Force recommends that Americans begin colorectal cancer screening at age 45.
See the original study here.
