Colon Polyps

Colorectal cancer almost always begins as a polyp that transitions into cancer over time.

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In most cases, polyps take years to grow into cancers. If you have/had a colorectal polyp, here's what you need to know.

What is a polyp?

A polyp is a small outgrowth of cells or tissue that occurs in the lining of the colon or rectum. Picture a pimple, but inside your colon or rectum. There are a few different types of polyps, and we know now that colorectal cancers begin as polyps.

Only a very small percent of polyps will become cancerous. Most polyps and early stage colorectal cancers do not cause symptoms that you can see or feel.

Polyp Symptoms

Most of the time, polyps don’t have 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.

Polyp Shapes

Pedunculated Polyps

Some polyps grow on the end of a stalk and look similar to a mushroom. These are called pedunculated polyps.

Sessile (or Flat) Polyps

Sessile polyps grow without the narrow stalk and lie flat against the wall of the colon. These are also known as flat polyps. Flat polyps refer to colon polyps with a plate-like shape and they are very common in the colon and rectum. They do not increase the risk of colorectal cancer. Since their shape makes them harder to see, they may be more likely to be missed compared to other types of polyps that grow on a small stalk.

Cancerous and Precancerous Polyps

Both pedunculated and sessile polyps can turn into benign (noncancerous), precancerous, or cancerous polyps. Knowing your polyp type – such as hyperplastic, inflammatory, hamartomatous, adenomatous, hyperplastic, and sessile serrated – is important to know your cancer risk.

Polyp Types

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. 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.

Adenomatous Polyps (Adenomas)

These are the most common polyp type and also the most common precursor to colorectal cancer. However, only a small fraction of adenomas will become colorectal cancers. 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.

When an adenoma is over 1 centimeter, it's an “advanced adenoma.” An advanced adenoma is a certain type of polyp that meets specific criteria: It is either large in size (>1 cm) or it has certain cellular changes (high-grade dysplasia, tubulovillous formations). This type of polyp is the most common type to transition into colorectal cancer over time.

Therefore, it's important to detect these polyps via screening and remove them via colonoscopy so cancer can be prevented.

Hyperplastic Polyps

Although common, they are not likely to become colorectal cancer over time unless caused by a hereditary (family-linked) condition.

Sessile-Serrated and Traditional-Serrated Polyps

These polyps have an appearance of a “saw tooth” border under the microscope and, in some cases, do progress to colorectal cancer. They are less common than adenomas.

Hamartomatous Polyps

Generally, these are noncancerous unless associated with a hereditary syndrome like Peutz-Jeghers, Cowden, or Juvenile polyposis (JPS). These polyps are very rare.

Inflammatory Polyps

These are also rare and can be seen in chronic diseases in the colon or rectum, like ulcerative colitis or Crohn’s disease.

What is Dysplasia?

Dysplasia describes how histologically advanced (how developed the polyp appears when viewed under a microscope) 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 to be cancer.

How Do I Know if I Have Colorectal Polyps?

There are many screening methods that can detect precancerous polyps:

  • Colonoscopy
  • Flexible sigmoidoscopy
  • CT colonography (virtual colonoscopy)
  • Stool DNA test (Cologuard®),
  • Fecal immunochemical test (FIT)
  • High-sensitivity guaiac fecal occult blood testing (FOBT).

All methods can detect polyps and and cancers to varying degrees. The benefits of some of the stool-based tests
(FIT, stool DNA) are that they are noninvasive tests and can be performed at home. But, they must be done more frequently
(every one to three years) because they are less sensitive in detecting cancer and polyps than colonoscopy.

The more invasive, direct visualization techniques (colonoscopy, CT colonography, flexible sigmoidoscopy) allow us to see the polyps. These can be done less frequently.

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 (where polyps and cancer develop at an earlier age).

How Many Colorectal Polyps is a Lot?

With some types of hereditary syndromes, which lead to an increased risk of colorectal cancer, a person may have 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 all polyps 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. 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 they 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 tissue 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 colorectal cancer is considered to be a preventable disease!

After a colonoscopy, the timing of the next one depends on the findings. If the exam was complete and you do not have any polyps, you will not likely need another colonoscopy for 10 years.

However, if you have many polyps or advanced adenomas, you will be asked to return for a repeat colonoscopy (surveillance colonoscopy) sooner — perhaps in three or five years.

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 5% to 10% 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 that you need to be screened every three to five years if polyps were found.

What if I Have a Cancerous Colon Polyp?

If you were diagnosed with a cancerous colon polyp, you were diagnosed with colorectal cancer, and we are here for you. You will need to schedule recommended follow-ups and talk to your doctor about who to include on your treatment team.

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

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

Are Polyps 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 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 getting screened 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.

Are certain populations more susceptible to developing advanced adenomas?

Advanced adenomas occur in men and women of all socio-demographic backgrounds, but they are more frequent with advancing age and among African-Americans.

Patients with a family history of advanced adenomas, or those who have personally had advanced adenomas, are more likely to develop them in the future.

Colon Polyp Q&A

Fight CRC president, Anjee Davis, interviewed Fola May, MD, PhD, and she unpacked our questions about polyps.

Colon Polyp Q&A with Dr. Fola May

Thank you to our education sponsors:

Medical Review

Dr. May Headshot
Folasade P. May, MD, PhD, MPhil


Last Reviewed: March 1, 2022