Colon Polyps: Understanding your cancer risk

Colorectal cancer usually starts as a small growth in the colon or rectum called a polyp. Over time, this polyp can become
cancerous. In most cases, polyps take years to grow into cancers. If you have polyps, here’s what you need to know.

Colon Polyps: Understanding your cancer risk

Colorectal cancer usually starts as a small growth in the colon or rectum called a polyp. Over time, this polyp can become cancerous. In most cases, polyps take years to grow into cancers. If you have polyps, here’s what you need to know.

What is a polyp?

Polyps are small growths in the colon or rectum lining. Picture a pimple, but inside your colon or rectum. Only a very small percentage of polyps and only certain types of polyps can become cancerous. Most polyps and early-stage colorectal cancers do not cause symptoms that you can see or feel.

What is a polyp?

Polyps are small growths in the colon or rectum lining. Picture a pimple, but inside your colon or rectum. Only a very small percentage of polyps and only certain types of polyps can 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 people, polyps bleed. This can cause red or black blood in the stool. Bleeding may be intermittent. It is always important to notify your doctor if you see bloody poop.

Polyp shapes

Colon polyps take on a few different shapes.

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

Sessile polyps grow without the narrow stalk and lie flat against the wall of the colon. These are also known as flat polyps. They are plate-shaped and are very common in the colon and rectum. 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.

Pedunculated, sessile, and flat polyps can be benign (noncancerous), precancerous, or cancerous.

Polyp types

Not all polyps are the same. Polyps come in different types as well.

Just because you have a polyp in your colon, that doesn’t mean it’s cancer. Few polyps grow into cancer.

Cancer risk is determined by how a polyp appears under a microscope. Advanced adenomas, sessile serrated polyps (also known as sessile serrated adenomas), and traditional serrated adenomas have the highest risk of becoming cancerous.

On the other hand, hyperplastic, inflammatory, and hamartomatous polyps are unlikely to become cancer.

Adenomas are one of the most common polyp types, and they are also the most common polyp type to turn into cancer. But, only a few adenomas actually into colorectal cancers.

Adenomas are described by growth patterns a pathologist makes when examining the polyp under a microscope.

Tubular growth pattern–generally applies to smaller adenomas growing in a tube shape.

Villous adenoma–generally applies to larger adenomas growing in a shaggy, cauliflower-like shape.

Tubulovillous –adenoma with a mixture of both tubular and villous growth patterns.

When an adenoma is over 1 centimeter or has tubular, villous, or tubullovillous features, it is called an “advanced adenoma.” Advanced adenomas increase the risk of colorectal cancer. It’s important to find and remove polyps early to prevent cancer from forming.

If you’ve had an adenoma in the past, you are more likely to develop new adenomas in the future. The number and size of adenomas helps determine how often you will need to repeat a colonoscopy.

It’s also very important to tell your blood relatives (parents, siblings, children) if you’ve had adenomatous polyps, because they are more likely to get them too. Like you, they will need to be screened for colorectal cancer more frequently. They may also need to start screening earlier.

Although common, hyperplastic polyps are not likely to become colorectal cancer over time unless they’re caused by a hereditary condition.

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

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

These are also rare and can be seen in chronic diseases in the colon or rectum, like ulcerative colitis or Crohn’s disease. They do not typically transform into colorectal cancer.

Dysplasia describes how developed the polyp appears when viewed under a microscope. All adenomas are dysplastic. Pathologists use the term “high-grade dysplasia” to distinguish polyps that appear to be seriously abnormal.

Polyp symptoms

Most of the time, polyps don’t have symptoms. However, for some people, polyps bleed. This can cause red or black blood in the stool. Bleeding may be intermittent. It is always important to notify your doctor if you see bloody poop.

Polyp shapes

Colon polyps take on a few different shapes.

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

Sessile polyps grow without the narrow stalk and lie flat against the wall of the colon. These are also known as flat polyps. They are plate-shaped and are very common in the colon and rectum. 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.

Pedunculated, sessile, and flat polyps can be benign (noncancerous), precancerous, or cancerous.

Polyp types

Not all polyps are the same. Polyps come in different types as well.

Just because you have a polyp in your colon, that doesn’t mean it’s cancer. Few polyps grow into cancer.

Cancer risk is determined by how a polyp appears under a microscope. Advanced adenomas, sessile serrated polyps (also known as sessile serrated adenomas), and traditional serrated adenomas have the highest risk of becoming cancerous.

On the other hand, hyperplastic, inflammatory, and hamartomatous polyps are unlikely to become cancer.

Adenomas are one of the most common polyp types, and they are also the most common polyp type to turn into cancer. But, only a few adenomas actually into colorectal cancers.

Adenomas are described by growth patterns a pathologist makes when examining the polyp under a microscope.

Tubular growth pattern–generally applies to smaller adenomas growing in a tube shape.

Villous adenoma–generally applies to larger adenomas growing in a shaggy, cauliflower-like shape.

Tubulovillous –adenoma with a mixture of both tubular and villous growth patterns.

When an adenoma is over 1 centimeter or has tubular, villous, or tubullovillous features, it is called an “advanced adenoma.” Advanced adenomas increase the risk of colorectal cancer. It’s important to find and remove polyps early to prevent cancer from forming.

If you’ve had an adenoma in the past, you are more likely to develop new adenomas in the future. The number and size of adenomas helps determine how often you will need to repeat a colonoscopy.

It’s also very important to tell your blood relatives (parents, siblings, children) if you’ve had adenomatous polyps, because they are more likely to get them too. Like you, they will need to be screened for colorectal cancer more frequently. They may also need to start screening earlier.

Although common, hyperplastic polyps are not likely to become colorectal cancer over time unless they’re caused by a hereditary condition.

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

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

These are also rare and can be seen in chronic diseases in the colon or rectum, like ulcerative colitis or Crohn’s disease. They do not typically transform into colorectal cancer.

Dysplasia describes how developed the polyp appears when viewed under a microscope. All adenomas are dysplastic. Pathologists use the term “high-grade dysplasia” to distinguish polyps that appear to be seriously abnormal.

How do I know if I have colorectal polyps?

There are many screening methods that can detect polyps, although some are much better and more effective than others:

  • Colonoscopy

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

All methods can detect polyps and cancers to varying degrees. Colonoscopy and flexible sigmoidoscopy allow doctors to both see and remove polyps during the same procedure.

How do I know if I have colorectal polyps?

There are many screening methods that can detect polyps, although some are much better and more effective than others:

  • Colonoscopy

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

All methods can detect polyps and cancers to varying degrees. Colonoscopy and flexible sigmoidoscopy allow doctors to both see and remove polyps during the same procedure.

How long does it take a polyp to turn into cancer?

An adenoma can become cancer in around 10 years. But sometimes it happens faster or slower. People with a genetic condition may get cancer quicker because polyps and cancer appear much earlier and grow quickly.

How long does it take a polyp to turn into cancer?

An adenoma can become cancer in around 10 years. But sometimes it happens faster or slower. People with a genetic condition may get cancer quicker because polyps and cancer appear much earlier and grow quickly.

How many colorectal polyps is a lot?

Some individuals may develop numerous polyps because of specific genetic conditions. Others may have only a few polyps. Whether you have many or just a few, it’s crucial to get rid of all polyps to avoid cancer.

Knowing what type and how many polyps the doctor found is crucial. This information should be shared with your blood-related family members. If you have a history of high-risk polyps, it could affect their chances of getting cancer.

How many colorectal polyps is a lot?

Some individuals may develop numerous polyps because of specific genetic conditions. Others may have only a few polyps. Whether you have many or just a few, it’s crucial to get rid of all polyps to avoid cancer.

Knowing what type and how many polyps the doctor found is crucial. This information should be shared with your blood-related family members. If you have a history of high-risk polyps, it could affect their chances of getting cancer.

What if polyps are found during a colonoscopy?

If you have polyps in your colon, your doctor likely performed a polypectomy to remove your polyp(s). Most patients are under sedation when this happens and don’t feel pain during or after. If a doctor performed a polypectomy, you will need to ask what type of polyps were removed and get a copy of the pathology report.

What if polyps are found during a colonoscopy?

If you have polyps in your colon, your doctor likely performed a polypectomy to remove your polyp(s). Most patients are under sedation when this happens and don’t feel pain during or after. If a doctor performed a polypectomy, you will need to ask what type of polyps were removed and get a copy of the pathology report.

When do I need another colonoscopy if my doctor found polyps?

The timing of your next colonoscopy depends on the pathology report. If you do not have any polyps, you will not likely need another colonoscopy for 10 years.

However, if you have one large or many small adenomas, you will be asked to return for a surveillance colonoscopy sooner—perhaps in 3 to 5 years.

These follow-up colonoscopies help doctors discover and remove any new polyps that developed since your last procedure.

Your doctor will encourage you to repeat your colonoscopy based on:

  • The size of polyp(s)
  • How many polyps in colon were found
  • The type of polyp(s)
  • Your family and personal history

The good news: Polyps don’t come back once removed.

When do I need another colonoscopy if my doctor found polyps?

The timing of your next colonoscopy depends on the pathology report. If you do not have any polyps, you will not likely need another colonoscopy for 10 years.

However, if you have one large or many small adenomas, you will be asked to return for a surveillance colonoscopy sooner—perhaps in 3 to 5 years.

These follow-up colonoscopies help doctors discover and remove any new polyps that developed since your last procedure.

Your doctor will encourage you to repeat your colonoscopy based on:

  • The size of polyp(s)
  • How many polyps in colon were found
  • The type of polyp(s)
  • Your family and personal history

The good news: Polyps don’t come back once removed.

What if I have a cancerous colon polyp?

If you were diagnosed with a cancerous colon polyp, you were diagnosed with colorectal cancer. You’ll need to quickly learn the stage of your cancer, as that will drive your next steps.

We are here for you.

If doctors find cancer, you can rest assured Fight CRC offers free resources to guide you every step of the way.

What if I have a cancerous colon polyp?

If you were diagnosed with a cancerous colon polyp, you were diagnosed with colorectal cancer. You’ll need to quickly learn the stage of your cancer, as that will drive your next steps.

We are here for you.

If doctors find cancer, you can rest assured Fight CRC offers free resources to guide you every step of the way.

Are polyps hereditary?

Some people may inherit a tendency for growing polyps. It’s important to ask your close family members about any history of colon or rectal cancer and/or pre-cancerous polyps.

Studies suggest first-degree biological relatives of patients with advanced adenomas and/or advanced serrated polyps face increased risk for colorectal cancer, and they need to discuss starting screening at a younger age and screening more frequently.

Additionally, people with Lynch syndrome or familial adenomatous polyposis (FAP) face a high risk for developing polyps.

Are polyps hereditary?

Some people may inherit a tendency for growing polyps. It’s important to ask your close family members about any history of colon or rectal cancer and/or pre-cancerous polyps.

Studies suggest first-degree biological relatives of patients with advanced adenomas and/or advanced serrated polyps face increased risk for colorectal cancer, and they need to discuss starting screening at a younger age and screening more frequently.

Additionally, people with Lynch syndrome or familial adenomatous polyposis (FAP) face a high risk for developing polyps.

Learn about the impact of genetics on colorectal cancer with our Genetics Brochure.

Learn about the impact of genetics on colorectal cancer with our Genetics Brochure.

Do some groups have a higher chance of getting advanced adenomas?

Advanced adenomas can happen in people of all backgrounds, but they are more common as people get older and in Black individuals.

People whose family members have advanced adenomas, or those who have had advanced adenomas themselves, are at higher risk of getting them again in the future.

Do some groups have a higher chance of getting advanced adenomas?

Advanced adenomas can happen in people of all backgrounds, but they are more common as people get older and in Black individuals.

People whose family members have advanced adenomas, or those who have had advanced adenomas themselves, are at higher risk of getting them again in the future.

Medical Review

Folasade P. May, MD, PhD, MPhil

UCLA

Date reviewed: December 13, 2023