Colon Polyps

What are colon polyps?

Colon polyps are growths on the inside lining of your colon (large intestine). They’re a type of tumor, a cluster or mass of abnormal cells. Polyps are tumors that grow out of the mucous lining inside your hollow organs, like your gastrointestinal tract, your nose or female reproductive organs.

Colon polyps are common, and many are harmless. But some types can grow into cancer if they aren’t removed. This is why healthcare providers look for polyps in your colon during a colonoscopy, an exam inside your colon. While polyps aren’t cancer, almost all colorectal cancer starts from a polyp. 

What are the different types of colon polyps?

Healthcare providers classify colon polyps in a couple of different ways. One way is by looking at the shape. If a polyp looks like a mushroom, with a “head” and “stalk,” they call it “pedunculated.” If it doesn’t have a stalk and looks more like a raised lump with a broad base, they call it “sessile.”

Providers also consider how polyps look under a microscope. Different types have different microscopic features because they grow and develop using different processes. These same processes also determine whether a polyp can grow into cancer or not. So, different types have different cancerous potential.

Types of colon polyps

Types of colon polyps include:

• Adenomatous polyps (adenomas).
  • Tubular adenomas.
  • Villous adenomas.
  • Tubulovillous adenomas.
• Serrated polyps.
  • Hyperplastic polyps.
  • Sessile serrated lesions.
  • Traditional serrated adenomas.
• Hamartomas (juvenile polyps).
• Inflammatory (pseudopolyps).

Neoplastic vs. non-neoplastic polyps

Healthcare providers classify colon polyps as neoplastic or non-neoplastic to indicate whether they can grow into cancer or not. Neoplastic polyps can grow into cancer. Non-neoplastic polyps can’t.

Neoplastic polyps include:

• All adenomatous polyps (adenomas).
• Sessile serrated lesions.
• Traditional serrated adenomas.

Non-neoplastic polyps include:

• Hyperplastic polyps.
• Juvenile polyps.
• Inflammatory pseudopolyps.

How common are colon polyps?

Colon polyps are common, especially as you get older. They affect about 20% of adults overall and about 40% over the age of 50, as well as 6% of children. People of all ethnicities and genders are at risk of colon polyps and colon cancer. They’re slightly more common in Western nations, in general.

What percentage of colon polyps are cancerous?

Most colon polyps have the potential to become cancerous, which is why healthcare providers remove them during a colonoscopy. But very few of them actually do turn into cancer, and it takes a long time for them to do so. Routine colonoscopies remove polyps before they have the chance to become cancer. 

Around 75% of colorectal cancers start from adenomatous polyps, and about 80% of all colon polyps are adenomas. But only about 5% of adenomas are actually malignant. The risk of a random, average-size colon polyp becoming cancerous is estimated to be 8% over 10 years and 24% over 20 years.

What are the symptoms of colon polyps?

Most colon polyps, and many colorectal cancers, won’t cause any symptoms. This is why screening — testing for diseases before you have symptoms — is so important. Usually, by the time you do have symptoms, the polyp has already turned into cancer.

Possible symptoms, though uncommon, include:

• Signs of colorectal bleeding. If you have bleeding polyps, you might notice blood in your poop or when you wipe. A slow bleed might not be visible, but after a while, you might feel it. You might develop iron deficiency anemia, which causes side effects like weakness and fatigue.
• Unexplained poop changes. Rarely, some people suddenly develop chronic diarrhea or constipation or start seeing excess mucus in their poop. These symptoms have many more likely causes than polyps, but they’re worth checking out, especially if you can’t explain them.

What causes colon polyps?

Most colon polyps are sporadic, which means they occur randomly. However, some people have hereditary syndromes, conditions passed down through their families, that cause colon polyps. These syndromes can cause large numbers of certain types of polyps and can carry a higher cancer risk.

What is the main cause of colon polyps?

Genetic mutations are the main cause of colon polyps. These are errors in the genetic code that your cells use to reproduce themselves. The cells in your colon lining replace themselves often, so there are more chances for errors to occur. When their code changes, they grow and behave differently. 

Some gene mutations are passed down through families (these are hereditary syndromes). Others appear to be random, but they probably have multiple contributing causes. Researchers believe that sporadic colon polyps may be partly inherited and partly triggered by environmental risk factors.

What are the contributing causes of colon polyps?

Genetics: You’re more likely to have sporadic colon polyps if you have a first-degree relative who’s had them. You may also have colon polyps associated with a specific hereditary syndrome. 

Genetic disorders that cause colon polyps include:

• Familial adenomatous polyposis (FAP).
• Peutz-Jeghers syndrome.
• MUTYH-associated polyposis.
• Gardner syndrome.
• PTEN hamartoma tumor syndrome.
• Turcot syndrome.
• Serrated polyposis syndrome.
• Juvenile polyposis syndrome.

Environment: Environmental risk factors are factors related to where and how you live that can affect your colon health. They include your physical environment, social environment and lifestyle habits. 

Environmental risk factors that may contribute to colon polyps include:

• Aging.
• Smoking.
• Heavy alcohol use.
• High-fat, low-fiber diet.
• Lack of exercise.
• Obesity.
• Diabetes.
• Inflammatory bowel disease.

Exceptions: Inflammatory pseudopolyps aren’t true polyps and aren’t caused by genetic mutations. They’re ulcers that healed to form bump-like scars that look like polyps. Chronic inflammation in your colon (colitis) is the usual cause of these ulcers. They’re often related to inflammatory bowel disease (IBD).

How are colon polyps diagnosed?

The best way to find and identify colon polyps is with a colonoscopy. This is an exam that looks inside your colon with a lighted camera. While other types of imaging tests can find colon polyps, a colonoscopy allows a healthcare provider to find and remove polyps during the same procedure.

Your healthcare provider can pass tools through the colonoscope to remove polyps or take tissue samples during your colonoscopy. They send these samples to a lab for further study. A pathologist examines the polyp samples under a microscope to identify the type and check for cancer cells. 

A colonoscopy does involve some preparation and the use of anesthesia, which may be difficult for some people. Healthcare providers may begin with simpler screening tests for these reasons. However, if another test did find colon polyps, you’d still need to have a colonoscopy to remove them.

Additional tests that may suggest colon polyps include:

• Blood tests. A complete blood count (CBC) may find evidence of anemia from chronic bleeding. A basic metabolic panel may find evidence of electrolyte imbalances. If you have a hereditary syndrome in your family, you might want to have genetic testing to find out if you have the same gene mutations or syndrome.
• Stool tests. A fecal occult blood test looks for microscopic traces of blood in your poop. Other tests look at DNA in your stool to look for changes that suggest cancer. 
• Imaging tests. Alternatives to the standard colonoscopy include virtual colonoscopy (a type of CT scan) and capsule endoscopy, (a colonoscopy conducted by a pill-sized video camera that you swallow). Polyps may also show up on a lower GI X-ray exam (also called a barium enema).

How many polyps are in a normal colonoscopy?

It’s normal to have anywhere from no colon polyps to a few. Healthcare providers pay attention to the number of polyps you have, as well as their size, location and type. Since polyps grow very slowly, having fewer and smaller polyps means you’re still at a relatively low risk of developing colorectal cancer.

You may be at a higher risk of developing colon cancer if you have:

• More than three polyps.
• Polyps larger than 10 mm (millimeters).
• Polyps in the right side of your colon (your sigmoid or transverse colon).
• Villous or tubuvillous adenomas.
• Sessile serrated lesions or serrated adenomas.
• A hereditary polyposis syndrome.

How are colon polyps treated?

The standard treatment is to remove colon polyps, unless you only have non-neoplastic types. Sometimes, a pathologist must examine them under a microscope before identifying them as neoplastic or non-neoplastic. It may take a week or two for your biopsy results and diagnosis to come back to you. 

Removing neoplastic polyps reduces your risk of developing colorectal cancer by 80%. But once you’ve had polyps, you’re likely to have them again. Your healthcare provider will judge your risk of future polyps based on the polyps you’ve had before. They’ll schedule your next screening based on that risk.

Colon polyp removal

Healthcare providers who conduct colonoscopies — usually, a gastroenterologist or colorectal surgeon — can remove most of your colon polyps during your screening. This simple procedure is called polypectomy. Occasionally, some polyps require special procedures to remove them (EMR or ESD).

Colonoscopy surveillance

If your colonoscopy doesn’t find any neoplastic polyps, you may not need another one for 10 years. But if you do have neoplastic polyps removed, this may change when you need to have your next screening. Your provider will recommend you come back in one, three, five, or seven years, depending on your personal risk factors.

Can I prevent colon polyps from forming?

There’s no way to prevent the genetic mutations that result in colon polyps. But you may be able to reduce your risk by taking good care of your general health. Eating more whole foods and fewer animal fats, getting some exercise and avoiding heavy drinking and smoking can help prevent colorectal cancer.

How serious are polyps in the colon?

Colon polyps can be serious because of their potential to turn into cancer. But most polyps aren’t cancerous when they’re found. Some might grow into cancer over time if they’re left untreated. Healthcare providers remove them when they find them to prevent this from happening.

What questions should I ask my doctor about my colon polyps?

You might want to ask:

• What type of colon polyps do I have?
• Are my polyps neoplastic (precancerous) or non-neoplastic (benign, or noncancerous)?
• Am I at low risk, average risk or high risk for developing colon cancer?
• Should I have genetic testing for hereditary polyposis syndromes?
• How fast do colon polyps come back after removing them?
• When should I have my next colonoscopy screening?

A note from Cleveland Clinic

Many people dread their routine colonoscopy screening and wonder if they can put it off. It might seem like a lot of trouble to go through just to confirm that you don’t have colon polyps. But if you do, a colonoscopy is your best chance of having them diagnosed and treated before you even know it.

It might be scary to learn that you have colon polyps, but many people do, and most will never get cancer. A colon polyp that’s been found and removed is one that you don’t have to worry about. The important thing is that it’s found and removed early enough to prevent cancer from starting.