The best screening test for colorectal cancer is the screening that gets done, because it decreases a person’s chances of getting colorectal cancer and significantly reduces their risk of dying from colorectal cancer.

This is the message that University of Colorado Cancer Center clinicians are emphasizing after national media coverage of a study published earlier this month in the New England Journal of Medicine offered potentially confusing perspectives on whether colonoscopy screening is effective for preventing cancer.

“One in 20 people who don’t get screened will get colorectal cancer,” says CU Cancer Center member Swati Patel, MD, an associate professor of gastroenterology in the CU School of Medicine. “Screening is safe, and it’s one of our best tools for preventing colorectal cancer.”

Media coverage of the study, which was conducted in Poland, Norway, and Sweden between 2009 and 2014, has resulted in some potentially confusing headlines that question whether colonoscopy, the most common preventive screening tool for colorectal cancer, is effective.

However, colonoscopy can detect adenomas, which are a type of polyp in the colon or rectum that can turn into cancer. Removing these polyps can prevent cancer altogether. Recently published research shows that for every 1% increase in adenoma detection rate during screening, there is a 3% decrease in colorectal cancer incidence and a 5% decrease in colorectal cancer mortality.

“Every country approaches public health and cancer prevention differently,” Patel explains. “Many countries in Europe take a population-based approach to cancer screening, so a study to see if a one-time invitation in the mail to get a colonoscopy works might make more sense. In the U.S., however, cancer screening is an important discussion between patients and their medical providers. There are a menu of screening options available, and here in the U.S., we make a shared and personalized decision with our patients about which one is the best test for them. Thus, results of a study where the general population was sent a random mailer don’t really apply to how we deliver care here in the U.S.”

Patel emphasizes that the European study did show that colonoscopy works. “Even though only 42% of those who received the mailed invitation ended up completing a colonoscopy, of those who did, there was a 31% reduction in their colorectal cancer risk and a 50% reduction in their risk of dying from colorectal cancer, compared with those who didn’t receive an invitation.”

The newly published research also brings attention to several important questions people might have about colorectal cancer screening, and colonoscopies in particular, which Patel addressed.

Are colonoscopies the only tool screening tool for colorectal cancer? 

There are actually multiple colorectal cancer screening options out there. Colonoscopy is the most commonly used in the United States, but the important thing for people 45 and older is to ask their doctor about their colon cancer screening options. There are stool-based tests, radiology tests, and of course colonoscopy, and there are advantages and disadvantages to each one.

The reason colonoscopies are often recommended is because they not only screen for cancer but help prevent cancer by detecting and removing adenomas in a “one-stop shop” before they become cancerous. Stool-based tests are designed to detect the by-products of cancer — microscopic blood or DNA markers that cancer cells shed into the stool. They’re designed to screen for cancer but not necessarily pre-cancerous polyps. It is important to note that if a non-colonoscopy test is abnormal, it requires a follow-up colonoscopy to determine why it is abnormal, and may require taking biopsies, removing polyps, or other treatment. We have these discussions with patients all the time to personalize the test that is the best fit for them. The best test is the test that gets done!

How do you address the apprehension or fear people might have about getting a colonoscopy? 

What I can emphasize is that we absolutely acknowledge that a colonoscopy takes time, it takes effort, it changes your lifestyle as you’re preparing for it, you might have to plan for a day off of work or time away from your family. We acknowledge this and do everything we can to help patients overcome those barriers. We offer sedation to lessen discomfort and we really work with patients to help them through any embarrassment or trepidation they might feel.

What does the preparation for a colonoscopy entail? 

I want to start by saying that as tough as the bowel preparation is, it is the single most important factor under a patient’s control to ensure they get a high-quality exam. Some precancerous polyps can be very subtle and obscured by even the smallest amount of debris. Thus, the better the prep, the better we are able to find and remove precancerous polyps. In general, preparation starts with a person being on clear liquids the day before the procedure, which helps get a jump start on bowel preparation. They take a certain volume of laxatives, and the amount is much lower than it used to be—half the night before the procedure and the other half the morning of the colonoscopy.

Preparation also usually includes not taking anything by mouth, except for the bowel preparation and medications, after midnight. We also require that the patient has someone bring them to the procedure and pick them up because of the sedation. By the time a patient gets checked in, gets all their questions answered, prepares for the procedure, and has it, it’s about a two- to three-hour process.

Some people worry about risk or that a colonoscopy is like surgery, so I always make sure I reassure my patients that colonoscopy is not surgery. The scope is just going in where stool comes out and there are no incisions, no post-procedure recovery or pain. When I do a procedure, I do a careful examination and the majority of polyps I see I’m able to remove right then and there. It’s very uncommon to have a complicated polyp or have one in a difficult location that requires a patient to come back for a second procedure.

Some patients might feel embarrassed to have this part of their body exposed or have concerns about modesty; how do you work with patients in these scenarios? 

First, it’s important to be open with patients and non-judgmental so that they feel they can bring these concerns to me. I emphasize that we do everything we can to protect patients’ privacy and their modesty, but if they feel embarrassed I let them know that I’ve seen a lot of butts and I honestly don’t remember your butt at all. But I do remember the polyp I took out of your colon. We don’t pay attention to any external stuff —the lights are off and my eyes are on the screen. The thing that’s going to impress us is how beautiful your bowel preparation is; you don’t need to worry about anything else.

Some people may still feel certain taboos to talking about bowel habits or to having their rear end exposed, so we always reassure them that we have a very diverse team. If they would feel more comfortable having an all-male or all-female team, if they have concerns about sedation or are worried about what happens if their bowel isn’t totally clear, then those are things we can work through with them. We work with each individual to accommodate their needs and customize a plan so they feel as comfortable and relaxed as possible.

What advice would you give people who may have read coverage of the study that was published recently and are feeling confused about whether to get a colonoscopy? 

I would say talk with your doctor about colorectal cancer screening. There are multiple options with colonoscopy being the most direct and complete visualization of the entire colon and rectum as a one-stop shop. They’re safe and they’re one of our most effective tools for decreasing the risk of getting colorectal cancer and the risk of dying from colorectal cancer.

This article was originally published October 13, 2022, by Fred Hutch News Service. It is republished with permission.