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

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

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

Some polyps grow on the end of a stalk and look similar to a mushroom (this is called a pedunculated polyp). Adenomas are polyps that 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 polyps 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 polyps – to know your cancer risk.

Keep reading to learn about your risks with these types of 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.

Colon Polyp 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.

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 Size of a Polyp 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.

What Types of Colon Polyps Probably Won’t Become Cancer?

Most likely, these polyp types won’t become cancer:

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.

What Types of Polyps Likely Will Become Cancer?

These types of polyps come with a cancer risk.

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!

Adenomas 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 growth pattern – 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 on the right side of your colon, 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, these polyps appear with a “saw tooth” (serrated) border of their glands, and they are considered precancerous polyps.

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

The general theory is that it takes about 10 years for an adenoma (precancerous polyp) 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 – or polyps that appear more worrisome for cancer.

Anyone can grow a polyp, and colon polyps are common. Can you do anything to prevent polyps? Yes and no. Your risk of developing a polyp 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 of colon polyps also increases if you smoke and/or if you are overweight. It is important to follow a healthy lifestyle to reduce your risk of polyps and cancer.

Answers to the most common questions we receive about colon and rectal polyps, such as:

• How do I know if I have polyps in my colon or rectum?
• What if polyps are found during a colonoscopy?
• Are polyps hereditary?
• What if I have a cancerous polyp?

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Colorectal polyps are irregular tissue growths that protrude from mucous membranes on the lining of the large intestine (colon) or rectum. The types of polyps that may become cancerous include adenomatous polyps (adenomas), hyperplastic polyps, and sessile-serrated and traditional-serrated polyps.

Colorectal polyps are irregular tissue growths that protrude from mucous membranes on the lining of the large intestine (colon) or rectum. They may be flat or may appear to be attached by a stalk (pedunculated). Colon polyps are the most common type of polyp.

There are a few different types of polyps, some of which have the potential to become cancerous. 

Types of polyps that may become cancerous include:  

• Adenomatous polyps (adenomas)
• Hyperplastic polyps
• Sessile-serrated and traditional-serrated polyps

Colorectal polyps often have no symptoms. When symptoms occur, they may include:

In addition to a physical examination, colorectal polyps are often diagnosed during screening to check for colon or rectal cancer. 

Tests for colorectal polyps include: 

A tissue sample (biopsy) may be taken of the colorectal polyp to determine if it is cancerous. 

What are risk factors for developing colon cancer? See Answer

Treatment for colorectal polyps involves removing them. This is usually done when they are found during a colonoscopy in order to eliminate the chance of them becoming cancerous. 

Surgical removal of colon polyps is called a polypectomy, which is performed through a colonoscope. 

About 2/3 of colon polyps are adenomas, which are polyps that may become cancerous.

It is believed to take about 10 years for an adenoma (precancerous polyp) to turn into cancer.

Because it takes such a long time for a polyp to become cancerous, colorectal cancer can often be prevented if precancerous polyps (such as adenomas) are detected and removed before they become cancerous (malignant). 

It’s not always possible to prevent colorectal polyps, but healthy lifestyle changes may help reduce the risk of developing some types of polys. 

https://www.uptodate.com/contents/colon-polyps-beyond-the-basics?search=colon%20polyps&source=search_result&selectedTitle=7~142&usage_type=default&display_rank=5 https://fightcolorectalcancer.org/

https://www.niddk.nih.gov/health-information/digestive-diseases/colon-polyps