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You may have heard or read in the news that a recent study in the New England Journal of Medicine has called into question the effectiveness of colonoscopy as a screening tool for colorectal cancer. If you — or a loved one — are about to schedule or go in for an appointment, rest assured you are doing what is best for your health. Colonoscopy continues to be the best way to detect and prevent colorectal cancer.

“Colonoscopy remains the proven gold standard. There are numerous concerns with the way data was collected and presented in this study,” explains Roger Klein, MD, chair of gastroenterology at Summit Health. “We continue to urge our patients to get regular colonoscopies to lower their risk of developing colorectal cancer and reduce cancer death.”

If it is time to go for your regular screening, you are probably wondering what this new research means. It is important to understand the details of the recent research which may not be covered in the news summaries. Here’s what you need to know about colonoscopy and a deeper dive into the findings of this new study.

1. Colonoscopy is proven to lower your risk of getting cancer.

A colonoscopy is not only a screening test, but if benign tumors or polyps are found they can be removed. Since polyps can turn into colon cancer in the future, removing them reduces the risk of developing cancer. The recent study confirmed this, however, the 18% reduction in risk of developing cancer was an underestimation. It compares the risk in patients invited to get a colonoscopy with those who had usual care.  However, you should know that less than half of the patients who were invited to have the procedure ever had the colonoscopy.

When you compare patients who actually had a colonoscopy to those who did not, there was a 31% reduction in risk of colon cancer.

2. Having a colonoscopy reduces your risk of dying from colorectal cancer.

The same limitation occurs in the study when they report the risk of dying of colorectal cancer: They compared patients invited for the test with those who had usual care. When you look at the subset of patients who actually had a colonoscopy there was a 50% reduction in mortality.

3. The goal of a colonoscopy is to identify and remove benign tumors or polyps that can turn into cancer in the future.

The quality of a colonoscopy can vary depending on the expertise of the physician performing the procedure, who is known as an endoscopist. At Summit Health, we use a tumor or adenoma detection rate (ADR) to measure the quality of our endoscopists. In the U.S., for example, endoscopists have an ADR close to 40%. And Summit gastroenterologists have an even better ADR than the national average.  By comparison, in the study, which was conducted in Norway, Poland, and Sweden, nearly 30% of the endoscopists had an ADR of less than 25%. This underestimated the benefits of the test.

4. The benefits of colonoscopy may be seen many years later.

Screening for colorectal cancer should begin at age 45.  Colonoscopy is generally repeated every 10 years in patients at average risk of developing colorectal cancer if no polyp is found. The researchers in the study only looked at patients over a single 10-year period. A longer window of time and follow-up is likely needed to show the full benefits of removing these early-stage polyps. 

5. Any reduction in colon cancer is significant and important. 

The study results confirm that colonoscopy prevents cancer. That means the procedure also reduces the need for colorectal cancer treatments including debilitating, time-consuming, and costly surgeries, chemotherapies, and immunotherapies.

“Prevention is still the best medicine,” adds Dr. Klein. “Colonoscopy is the most effective tool we have in preventing colorectal cancer. It is important that patients who hear this news do not think they should delay or cancel their procedure.”