Proper screening is still the best way to prevent colorectal cancer

By Jessica Saenz

Colorectal cancer, also known as bowel cancer, is not unique in the way it forms or spreads. And as the fourth most common type of cancer in the U.S., it isn't rare. But among cancer types, colorectal cancer is unique in one important way: With regular screening, it can usually be prevented.

"Bowel cancer is extremely unusual among cancers. In theory, it's almost completely preventable," says James East, M.D., a gastroenterologist at Mayo Clinic Healthcare in London.

Even as screening technology and awareness improves, colorectal cancer — which includes cancer that begins in the colon and rectum — is the second leading cause of cancer-related deaths in the U.S.

Help change this statistic by learning and sharing the proper colorectal cancer screening guidelines this March during Colorectal Cancer Awareness Month:

The recommended age to begin colorectal cancer screening is 45, but there are exceptions.

In 2021, the U.S. Preventive Services Task Force updated its colorectal cancer screening guidelines to recommend that people begin routine screening at 45 — five years earlier than previously recommended.

"What we're seeing now is more people developing colorectal cancer under the age of 50. In fact, 10% of colorectal cancer cases now occur in people under the age of 50," says Lisa Boardman, M.D., a Mayo Clinic gastroenterologist.

"With average-risk screening starting at age 45, the hope is that cancer would be caught earlier or, even better, caught at the polyp stage, which is the precancerous lesion," she says. "The benefit of finding it at that stage is that you can remove a polyp and prevent that person from getting cancer."

Even sooner than age 45, it's important to talk to your health care professional about factors that might increase your risk of colorectal cancer and how they might affect your screening frequency and test type.

Risk factors include:

  • Black American, Native American and Alaskan Native ancestry.
  • A personal history of colorectal cancer or polyps.
  • Inflammatory intestinal conditions like ulcerative colitis or Crohn's disease.
  • Radiation therapy for cancer that was directed at the abdomen.
  • A family history of colon cancer.
  • Certain inherited gene mutations.

If you are a colorectal cancer survivor, or you have a family history of colorectal cancer, talk to your health care team about genetic testing to uncover gene mutations that could increase your risk of developing colorectal cancer, as such mutations also can affect your screening recommendations.

Several types of colorectal cancer screening tests are available.

A colonoscopy is still one of the most sensitive screening tests available for colorectal cancer. In addition to providing a thorough view of the colon and rectum, colonoscopies allow your physician to take tissue samples for biopsy and remove abnormal growths, also known as polyps, before they can become cancerous.

The prep work and process of a colonoscopy can feel overwhelming or invasive to some people. "Colonoscopy prep is a difficult thing, and it probably is the thing that patients like the least about having a colonoscopy," says Dr. East. But preparing for your colonoscopy can be a made a little less unpleasant.

While a colonoscopy might be one of the more familiar options for screening, a wider range of screening tests are now available that you can discuss with your health care team, including some you can do in the comfort and privacy of your own home.

"For those who would prefer a less invasive test, we can now do fecal immunochemical testing, or FIT. This is a sensitive test for blood in stool. If blood is found, we will proceed to arrange a colonoscopy for the patient," says Dr. East, adding that a stool DNA test may be used in combination with FIT to improve accuracy. Not everyone is a candidate for FIT, however. If you have a history of colorectal cancer or other risk factors, your health care professional may recommend more thorough screening tests.

Other types of screening tests you can discuss with your health care team are CT colonographies, which use CT scan images to create a detailed view of the colon and rectum, and flexible sigmoidoscopies, which require less prep but don't offer a view of the entire colon.

It's important to weigh your screening test options with your health care team and confirm insurance coverage.

With more options for colorectal cancer screening tests available, you might find yourself leaning toward one test over another. Before choosing an option, have a discussion with your health care team. During this discussion, your health care team can assess your risk factors, and family and personal history. Together, you can decide on a screening regimen that meets your needs and gives you the best possible surveillance.

When discussing your options with your health care team, it's important to also consider your attitude toward each test and your willingness to commit to regular screenings.

"The best screening tool is the one you're willing to get," says Dr. East. "There's no point in being set up for a colonoscopy if you're not willing to come for it. And there are a wide range of options now for bowel cancer screening — all of which provide substantial protection against bowel cancer."

Although several options for screening are now available, be sure to talk to your insurance provider about which tests might be covered under your plan and consider if you would be willing or able to pay any out-of-pocket costs.

Artificial intelligence (AI) could soon help with colorectal cancer screening.

Newer, more accessible methods of screening, like fecal immunochemical testing and stool DNA tests, are helping more people get screened for colorectal cancer and potentially detect cancer earlier, when it is more treatable. Researchers hope technology and the use of AI in colorectal cancer screening can further improve screening methods.

"I think the role of AI in endoscopy is huge. And it's coming to clinical care," says Dr. East. "This is really translating facial recognition technology, but instead of recognizing faces, the AI recognizes polyps at an astonishing rate during a live colonoscopy. This is really a game-changer for us."

Although AI tools for enhanced colorectal cancer screening are still in clinical trials, Nayantara Coelho-Prabhu, M.B.B.S., a Mayo Clinic gastroenterologist with a research focus on endoscopy, says AI-assisted colonoscopies could soon become a part of routine screenings.

Through databases of images and video, Dr. Coelho-Prabhu and colleagues are working to fine-tune AI tools to better detect polyps and surrounding tissue that, if left behind, could form a new polyp.

"Overall, the advances provided by AI-based learning can help us determine the best treatment option for each patient, and this will enhance our ability to offer patients truly individualized therapeutic approaches," says Dr. Coelho-Prabhu.

As you near the age of regular colorectal cancer screening, or you near your next exam, know that though you might experience some discomfort, regular screening for colorectal cancer can be preventive and even lifesaving.


"This is such an exciting time. With new equipment, new screening tests and Al, colorectal cancer is a preventable disease," says Dr. East. "This is a time when bowel cancer screening could really push colorectal cancer down to an absolute minimum."

The thought of a colonoscopy or any stool-related test might never be pleasant, but consider this: The peace of mind you can gain from an uneventful screening will surely outlast the feelings of embarrassment.

Learn more:

Watch Dr. Boardman discuss colorectal screening guidelines in this "Mayo Clinic Q&A" podcast video:

Watch Dr. East discuss colorectal cancer screening advancements in this "Mayo Clinic Q&A" podcast video:

Learn more about colon and rectal cancer, and find a colorectal cancer clinical trial at Mayo Clinic.

Join the Colorectal Cancer Group on Mayo Clinic Connect.