Colon Polyps

Colorectal cancer often takes many years to grow, and nearly all cases start off as a polyp. Here’s everything you need to know.

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What Are Colorectal Polyps?

A polyp is a group of cells that grow together. It occurs when these cells grow on the inside of the colon or rectum. There are a few different shapes.


Pedunculated Polyps

Some polyps grow on the end of a stalk and look similar to a mushroom (this is called a pedunculated polyp). Adenomas grow like a mushroom with a stalk.

Sessile (or Flat) Polyps

Sessile polyps grow without the narrow stalk and seem to lie flat against the wall of the colon. These are also known as flat polyps. Sessile only means that they don’t have a narrow stalk. It’s possible for a large, protruding polyp to have a sessile base.

Cancerous and Precancerous Polyps

Both pedunculated and sessile polyps can turn into benign (non-cancerous), precancerous and cancerous polyps. It’s important to know your polyp type – such as hyperplastic, inflammatory, hamartomatous, adenomatous, hyperplastic and sessile serrated – to know your cancer risk.

Keep reading to learn about your risks.

How Do I Know if I Have Colorectal Polyps?


If your doctor finds a polyp during your colonoscopy, it will most often either get removed immediately or biopsied (if it cannot be fully removed).

CT Colonography

CT colonography also offers a visualization of your colon and lets your doctor look for polyps. If any polyps are detected during a CT colonography, a follow-up colonoscopy will be scheduled so the doctor can remove it.

FIT-DNA for At-Home Screening

While colon cancer screening tests like FIT-DNA and FIT don’t actually “see” polyps, test results from some of these at-home screening tests can point health care providers to a need for additional testing.

Do Colon Polyps and Rectal Polyps Show on a CT Scan?

A CT colonography is a type of CT scan, and this is the only CT screening option that will detect colon polyps.


It’s hard to know if you have polyps because they don’t usually cause symptoms until they develop into cancer. This is why screening is important!

Screening for colorectal cancer = screening for polyps.

Most polyps can be safely removed during a colonoscopy, thus removing the risk of the polyp growing into cancer.

Most of the time, polyps don’t come with any symptoms. However, for some, polyps bleed. Bleeding may be intermittent. It is always important to notify your doctor if you notice blood in your stool.

Talk to your doctor if you experience rectal bleeding, a change in bowel habits, pain, and anemia. This could mean you have a polyp and you need to be screened, or that you need additional surveillance. Learn more about the symptoms of colorectal cancer.

Q&A with Dr. Fola May

Fight CRC president, Anjee Davis, interviews Fola May, MD, PhD as she unpacks all the questions you may have about polyps. Thanks to Geneoscopy for their support of Fight CRC's polyp education and making this video possible. For more, check out our downloadable free resource, "All About Polyps."

Colon Polyp Q&A with Dr. Fola May

Types and Risks

Just because you have a polyp, that doesn’t mean it’s cancer (also called a malignant tumor). Some polyps grow into cancer, but others may not.

Does the Colon Polyps Size Impact Cancer Risk?

Your cancer risk does increase with the size of the colon polyp, but there is no specific, generalized size that indicates a polyp is becoming cancerous.

However, one centimeter is the cutoff between an “advanced” and “non-advanced” polyp.

If you grow an advanced polyp, your doctor will likely ask you to return for a follow up sooner than normal. Not all polyps will become cancerous, but it is important to remove them all to block the possibility.

colon polyp size and type adenoma polyp

Colon Polyps Types

Most likely, inflammatory and hamartomatous polyps won’t become cancer. Adenomas, hyperplastic and serrated come with a cancer risk. It's important to ask your doctors any questions about your pathology report.

Inflammatory Polyps

These colon polyps are often seen with ulcerative colitis or Crohn’s disease, inflammatory bowel diseases (IBD). Although the polyps are generally non-cancerous, if you have IBD, you are at increased risk of colorectal cancer.

Hamartomatous Polyps

Hamartomatous polyps are generally noncancerous, unless they are found in people with a polyposis syndrome like Peutz Jaeghers, Cowden’s, or Juvenille Polyposis, in which case they are associated with the development of colorectal cancer. Learn more about genetic syndromes.

Adenomatous Polyps (Adenomas)

These polyps are a big deal! Approximately two-thirds of colon polyps are adenomas – that means 66 percent of all colon polyps are precancerous and mean you could develop colon cancer.

Adenomas are precancerous polyps in colon. They are described by growth patterns, or microscopic descriptions a pathologist makes to determine how often you need to return for a colonoscopy.

  • Tubular growth pattern – generally applies to smaller adenomas growing in a tube shape, less than half an inch in size
  • Villous adenoma – generally applies to larger adenomas growing in a shaggy, cauliflower-like shape
  • Tubularvillous – adenoma with a mixture of both tubular and villous growth patterns

If you’ve had an adenoma in the past, you are likely to develop new polyps, and you may need to be screened more often. It’s also very important to tell your family if you've had adenomatous polyps.

Hyperplastic Polyps

If a hyperplastic polyp is found in part of the colon, on the right side, some research suggests the polyp could become cancerous. However, if not linked to a hereditary syndrome, hyperplastic polyps generally do not carry a cancer risk.

Sessile-Serrated and Traditional-Serrated Polyps

Histologically, sessile-serrated polyps and traditional-serrated polyps appear with a “saw tooth” (serrated) border of their glands, and they are considered precancerous.

How Long Does it Take a Polyp to Turn into Cancer?

The general theory is that it takes about 10 years for an adenoma to turn into cancer. This varies for those with a hereditary syndrome (people who often see polyps and cancer at an earlier age).

What is Dysplasia?

Dysplasia describes how histologically advanced your polyp is, and all adenomas are dysplastic. Pathologists use the term “high-grade dysplasia” to distinguish polyps with more advanced histology – those that appear more worrisome for cancer.

How Many Colorectal Polyps is a Lot?

Some types of hereditary syndromes, which lead to an increased risk of colorectal cancer, could leave a person with hundreds of polyps. For others without a genetic link, just one or a few may grow. No matter the number, it is important to have the polyp(s) removed to prevent cancer.

It is important to know how many polyps your doctor found – and to relay that information to your first-degree relatives! Your personal history could impact their cancer risk and when they need to be screened.

What if Polyps are Found During a Colonoscopy?

If you underwent a colonoscopy, your doctor likely performed a “polypectomy” and removed your polyp(s) as your large intestine was examined. Does it hurt? Not generally. Most patients go under sedation when this happens and don’t feel pain during the polyp removal or afterward. If a doctor performed a polypectomy, you will need to follow up to find out what type of polyps he/she removed.

  • Polyp completely removed? The entire polyp will be sent to a pathology laboratory for histology.
  • Polyp cannot be entirely removed? It will typically get biopsied during the colonoscopy, and your doctor will send the biopsy to the pathology laboratory to determine the histology.
  • Polyp too large to grasp and snip off during a colonoscopy? Although rare, a follow up surgery may be required.

Removing the colon polyp can stop the growth of colorectal cancer if it’s done early enough. This is why colorectal cancer screening is so important, and why it’s considered to be a preventable disease!

The type of polyp your pathologist describes in the lab report will determine what comes next. For example, if you had small hyperplastic polyps, you may not need to do anything more than get a colonoscopy every 10 years, which is the recommendation for average-risk individuals.

If you have precancerous polyps/adenomas, you will likely need more regular follow up. The good news: Polyps don’t come back once removed. However, after polypectomy, your risk of developing new polyps is high – about five to ten percent per year for the first several years.

Your Follow Up Will Depend On:

  • The size of polyp(s)
  • How many polyp(s) are found
  • The type of polyp(s)
  • Where the polyp(s) are located in the colon or rectum
  • Your family and personal history

Don’t be surprised if your doctor recommends you need screened three to five years.

Are They Hereditary?

Some people carry a hereditary predisposition to colorectal cancer and polyps. That’s why it is important to talk to your first-degree relatives and learn if you have a family history of colon cancer and/or rectal cancer.

Studies suggest first-degree relatives of patients with advanced adenomas and/or advanced serrated polyps face increased risk for colorectal cancer, and they need to discuss screening sooner with their health care provider.

Additionally, people with Lynch syndrome or familial adenomatous polyposis (FAP) face a high risk for developing polyps. Learn more about this in our Genetics Mini Magazine and our Hereditary Colorectal Cancer webinar.

What if I Have a Cancerous Colon Polyp?

If you were diagnosed with colorectal cancer, we are here for you. You will need to schedule recommended follow ups and talk to your health care provider about who to include on a treatment team.

If doctors find cancer, you can rest assured there are resources to help you with a variety of things including making treatment decisions, understanding terminology, working through anxiety and fear, and more. There are even resources for your loved ones.

It is always a good idea to seek a second opinion at any time.


Anyone can grow a polyp, and they are common. Can you do anything to prevent polyps? Yes and no. Your risk increases with age, which you cannot control, as well as if you have personal or family history of polyps and/or colorectal cancer. However, your risk also increases if you smoke and/or if you are overweight. It is important to follow a healthy lifestyle.

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