Are all colon polyps precancerous or worse?

A colon polyp is a small growth that can develop anywhere in the large intestine. Colon polyps are often precancerous, but unlike other precancerous indicators in the body, they can easily be removed as they are found during a colonoscopy — a cancer screening that internally examines the entire length of your large intestine.

"The chance of your doctor finding a precancerous colon polyp during colonoscopy is as high as 40%," said Bruce Sand, DO, an HonorHealth gastroenterologist. If that colon polyp is a specific type and is not discovered and removed during colonoscopy within 10 years after it forms, there's a high probability it will develop into cancer.

A gastroenterologist, the specialist who usually performs a colonoscopy, can't tell for certain if a colon polyp is precancerous or cancerous until it's removed and examined under a microscope. "In the future," Dr. Sand said, "artificial intelligence may help doctors determine during a colonoscopy which polyps are more likely to be precancerous."

Completely preventable cancer

The good news is that, with advances in screenings, colon cancer is preventable. Here’s what we know:

  • As often as 40% of the time, a precancerous polyp — frequently a type called an adenoma — is found during a screening colonoscopy.
  • Colon cancer is found during only in about 40 out of 10,000 screening colonoscopies, Dr. Sand said.
  • Colonoscopy is the only cancer screening technique that can actually prevent cancer and not just detect it.
  • Removing a precancerous or benign polyp eliminates the risk of colon or rectal cancer from developing from that growth.
Colon polyps - Are they precancerous or worse?

To underscore the importance of a screening colonoscopy, consider this — for men and women combined, colon cancer is the second leading cause of cancer death. According to the American Cancer Society, more than 52,000 Americans are expected to die this year alone from colon cancer.

"The only difference between someone living and dying from colon cancer is when — at what point in their life — they get their colonoscopy," Dr. Sand said. "Colonoscopy really can save your life."

What to know about colon polyps

Doctors don't know why colon polyps form, and not every type of polyp is considered precancerous. However, two-thirds of polyps found through colonoscopy are likely precancerous, Dr. Sand said. These are called adenomas, and once they are painlessly removed through colonoscopy, they present no further risk to the patient.

Did you know?

  • If you don't have any risk factors for colon cancer (no family history and no lifestyle risks listed below), you should have a screening colonoscopy at least every 10 years beginning at age 45.
  • African-Americans are more prone to developing adenomas in the colon, but doctors don't know why.
  • If you're African-American, your doctor may recommend a screening at an earlier age.
  • If you have any risk factors, your doctor may recommend a first screening colonoscopy at an even earlier age.

After television personality Katie Couric's husband died from colon cancer in 1998, Couric was determined to make screening a familiar, commonplace occurrence for everyone in the U.S. because it would save lives. Since around the turn of the 21st century, traditional colonoscopy has been the gold standard for colon cancer screening.

Although there are other types of screening, only traditional colonoscopy allows for the removal of polyps during the procedure.

Most risk factors can be minimized

Five risk factors that contribute to colon cancer are:

  • Family history, which can't be changed but can affect how your risk is managed
  • Obesity, especially abdominal obesity
  • Smoking
  • Alcohol consumption
  • Red meat consumption

"For every five numbers your body mass index (BMI) climbs, you face a 19% increased risk of colon cancer," Dr. Sand said. "It's best to lose weight, exercise regularly, quit smoking and cut back on alcohol and red meat consumption."

And, he said, "don't put off getting a screening colonoscopy. It's one of the best things you can do for your health."

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