Colon Polyps

Medically Reviewed by Zilpah Sheikh, MD on May 17, 2024
Written by WebMD Editorial Contributors
9 min read

Colon polyps are small growths on the lining of your colon or large intestine, part of your digestive tract. Most aren’t harmful. But some can turn into colon cancer over time. For that reason, your doctor needs to remove any colon polyps you have.

How common are colon polyps?

From 15% to 40% of adults are thought to have colon polyps. They're most likely to affect men (and those assigned male at birth) and people over 50.

 

Changes in genes (called mutations) cause most colon polyps. Doctors don’t know exactly why these changes happen.

Anyone can get colon polyps, but certain things make you more likely to have them, including if you:

Black people are at higher risk for colorectal cancer than other ethnic groups but are thought to get colon polyps at similar rates. This may be due to differences in access to high-quality screening and treatment.

Some genetic conditions also raise your chances for polyps and colon cancer, including:

Familial adenomatous polyposis (FAP). This can cause hundreds or thousands of polyps to grow when you’re young, as early as your teenage years.

Gardner’s syndrome. This is a type of FAP that causes polyps to grow in your colon and small intestine. It may also cause noncancerous tumors in other parts of your body.

Lynch syndrome. Also known as hereditary nonpolyposis colorectal cancer or HNPCC, it causes polyps that are very likely to become colon cancer.

MYH-associated polyposis (MAP). A problem with the MYH gene causes many polyps to grow or colon cancer to happen at a young age.

Peutz-Jeghers syndrome. The condition starts with freckles that show up all over the body. It also causes colon polyps that can become cancer.

Serrated polyposis syndrome. This causes a specific type of polyp, serrated adenomatous polyps, to grow in the upper part of the colon. They can turn into colon cancer.

If you have one of these conditions, your doctor will recommend regular screening tests to look for problems early.

Alcohol and colon polyps

Having more than three alcoholic drinks a day increases your risk of colon polyps, especially if you also smoke.

What foods cause colon polyps?

Studies have shown that eating less of these foods could lower your risk of polyps:

  • Processed meat, like bacon and deli meats
  • Red meats, like pork and beef
  • High-fat foods, such as fried items 

Not all polyps are the same, and not all can become cancerous. Doctors divide colon polyps into types based on their characteristics and how they look under a microscope. Some of the more common types of colon polyps include:

Adenomatous polyps (adenomas)

About 70% of all colon polyps are this type. Only a few go on to become cancerous, though most colon cancers start as this type. It usually takes years for an adenoma to turn into cancer.

There are subtypes of adenomatous polyps, based on their growth patterns:

Tubular ademonas.  These are small adenomas, usually less than 1/2 inch, that grow in a tube shape.

Villous adenomas.  These are larger than the tubular type. They grow in a shape that resembles a cauliflower.

  • Tubulovillous adenomas. This type grows in a way that combines villous and tubular patterns.  

Serrated polyps 

These are named for their saw-tooth-like edges. Some types can turn into cancer, though they do so in different ways than adenomas. Subtypes include:

Sessile serrated.  "Sessile" means they're attached directly to the colon wall.  

Traditional serrated. These look similar to adenomas but also have serrated growth patterns. Both traditional and sessile serrated polyps are considered precancerous.

Hyperplastic polyps. This type is unlikely to turn into cancer.

Hamartomas, or juvenile polyps

This type of colon polyp is very rare. They're not cancerous unless they form due to a genetic conditionlike Cowden syndrome, Peutz-Jeghers syndrome, or juvenile polyposis.

Inflammatory (also called pseudopolyps)

These most often affect people with inflammatory bowel disease (IBD). They're not considered true polyps because they grow in reaction to long-lasting inflammation. They can't turn into cancer.

What percentage of colon polyps are cancerous?

Some types are more likely to turn into cancer than others. But if left untreated, an average-size polyp has about an 8% chance of turning cancerous over 10 years and a 24% chance of becoming cancer within 20 years. 

What is the difference between colon polyps and colorectal polyps?

They're essentially the same -- a growth in the lining of your colon or rectum. "Colon polyp" may be used as a shorter term for "colorectal polyp."  Or a polyp on your rectum could be described as a rectal polyp and polyps in your colon called colon polyps.

The appearance of a colon polyp gives doctors clues about what type it is and how serious it may be. 

Colon polyps size

In general, the larger a polyp is,  the more likely it is to be cancerous. A small polyp might be the size of a matchstick head, while a very large one could be the size of your thumb. 

Colon polyps: sessile

A sessile colon polyp is a dome-like growth that grows directly against the wall of your colon. The vast majority of colon polyps are sessile. Its fairly easy for your doctor to remove them during a colonoscopy.

Pedunculated colon polyps

This type grows from a stalk, similar to a mushroom. The head or top of a pedunculated polyp can become cancerous. They're easy for your doctor to see and remove while you're having a colonoscopy.  

  • Flat polyps

    These grow flat against your colon wall. They're uncommon. Flat polyps are harder for your doctor to see and remove than other shapes.

    Colon polyps dysplasia

    "Dysplasia" refers to how cancerous cells look when examined under a microscope. With high-grade dysplasia, the polyp cells are disorganized, grow too fast, and have larger, darker centers than normal cells. Low-grade dysplasia means they look only slightly different from normal cells.

Most colon polyps don’t cause symptoms. You probably won’t know you have one unless a test finds it. If you do have signs, they can include:

  • Blood in your poop, in the toilet bowl, or on toilet paper when you wipe. These could be signs of bleeding inside your colon.
  • A bowel movement that's black or has red streaks, which may mean there’s blood in it
  • Constipation or diarrhea that lasts longer than a week
  • Belly pain
  • Fatigue or shortness of breath. These can be signs that your body doesn’t have enough iron, which can happen if polyps bleed.

Talk to your doctor if you notice any of these signs. They don’t always mean that you have colon polyps or colon cancer. Other things like hemorrhoids, tears in the tissue inside your bottom, or some medicines can cause these symptoms.

Do colon polyps cause pain?

Colon polyps don't usually hurt. But you could have cramps in your belly area if an especially large polyp blocks part of your bowel.

 

It’s important to spot polyps early to prevent colorectal cancer. There are several kinds of screening tests. Your doctor can take out polyps during some of them.

Screening tests for colon polyps include:

Colonoscopy. About 1-3 days before the test, you’ll go on a clear liquid diet and take a laxative to clear out your colon. Your doctor will give you medicine so you’re not awake during the procedure. They use a long, thin, flexible tube with a light and camera at the end to look at the inside of your colon. They can also remove most polyps and send them to a lab to check for cancer. This test takes about 30 minutes.

CT colonography. Also known as a virtual colonoscopy, this uses X-rays and a computer to take pictures of your colon from outside your body. Your doctor can’t take polyps out during this test. If they spot any, you’ll need to have a regular colonoscopy. You’re awake for this test, but you’ll still need to do a special diet to clear out your bowel beforehand.

Flexible sigmoidoscopy. This test is similar to a colonoscopy, but you don’t have to do as much bowel prep. You might take medicine that helps you relax during the procedure. Your doctor puts a thin tube with a light into your bottom to look only at the lower part of your colon. If you have a polyp, they can remove it during the test. It takes about 20 minutes.

Stool tests. A FOBT (fecal occult blood test) and a FIT (fecal immunochemical test) look for tiny traces of blood in your poop. Stool DNA tests check for gene changes. For any of these tests, you collect a poop sample at home and take it to your doctor’s office or send it to a lab. If the tests find problems, you’ll need to have a colonoscopy.

Lower gastrointestinal series (barium enema). Before this test, the radiologist will fill your large intestine with a chalky liquid called barium. This makes your colon easier to see during an X-ray.

Are all colon polyps seen on a CT scan?

Screening CT colonography, sometimes called virtual colonoscopy, uses CT technology to take hundreds of images of your colorectal area. Together, these images give your doctor a detailed view inside your colon and rectum. CT colonography can detect cancer and large polyps at about the same rate as traditional colonoscopy, though it may not be as likely to find smaller polyps.

You don't need to be sedated before a virtual colonoscopy. Before you get one,  you'll do the same type of bowel-cleaning prep as you would with a colonoscopy. If your doctor finds polyps that need to be removed, you'll have that done during a traditional colonoscopy.

 

 

Colon polyps removal

During a colonoscopy or flexible sigmoidoscopy, your doctor uses forceps or a wire loop to remove polyps. This is called a polypectomy. If the polyp is too large to take out this way, you may need surgery to remove it. Once it’s out, a pathologist tests it for cancer.

Surgery

If you have a genetic condition like familial adenomatous polyposis, your doctor may recommend surgery to remove part or all of your colon and rectum. That’s the best way to prevent colon cancer for people with these health problems.

How fast do colon polyps grow back?

When your doctor completely removes a colon polyp, it's not likely to come back. But at least 30% of people who get polyps removed eventually develop new ones. Your doctor will likely recommend follow-up screening in 3-5 years.

 

While there's no way to prevent the gene changes that lead to colon polyps, regular screenings can go a long way to protect you against colorectal cancer. Adopting good health habits might also help reduce your risk. For example:

  • Follow a diet rich in fruits, vegetables, and fiber-rich foods like beans, lentils, peas, and high-fiber cereal.
  • Lose weight if you’re overweight.
  • Limit red meat, processed meats, and foods that are high in fat.
  • Talk to your doctor about whether calcium and vitamin D supplements are right for you. Some studies suggest they could lower your odds of colon cancer, but others don't.
  • If you have a family history of colon polyps, ask your doctor if you should get genetic counseling and when you should start screening for polyps.
  • Talk to your doctor about taking aspirin regularly. There's some evidence that daily aspirin might help keep colon polyps from turning cancerous. But it's not right for everyone since it could cause side effects like bleeding in your intestines or stomach.

Colon polyps are small, usually harmless growths on the lining of your colon (large intestine). But they sometimes turn cancerous over time. Your doctor will remove polyps if they're found during a colonoscopy. 

How serious are polyps in the colon?

Colon polyps are usually harmless. If you have large or multiple polyps, they're more likely to turn into cancer. If it's not removed, an average-size polyp has about an 8% chance of becoming cancerous within 10 years. Over 20 years, the chance increases to 24%. 

Should colon polyps be removed?

As a general rule, doctors remove any polyp they find during a colonoscopy. This reduces the odds that colorectal cancer will develop. 

Can a doctor tell if a polyp is cancerous during a colonoscopy?

While your doctor might suspect a polyp is cancerous, they don't know for sure until the polyp is examined under a microscope during a biopsy.