All About Colon Polyps

What is the colon?

The colon and rectum make up the last part of your digestive tract. Your digestive tract is made up of your mouth, esophagus, stomach, small bowel, and large bowel. Your colon is a tube that is about 5 to 6 feet long, connects to about 6 inches of rectum, and ends with your anus. 
Your colon has many parts. Here they are listed in the order that stool travels through:

• The cecum and ascending colon (on your right side).
• The transverse colon (goes across your abdomen/belly).
• The descending colon (on your left side),
• The sigmoid colon.

The cecum connects to your small intestine, while the sigmoid colon connects to your rectum. The colon's job is to change liquid waste into solid stool. Stool can spend 10 hours to many days in the colon before leaving your body through your anus.

What is a colon polyp?

A colon polyp is a mass or small growth of tissue on the inside wall of your colon. It sticks out from your colon wall. Colonic polyps are common. Polyps often do not cause any symptoms.

If there are symptoms from colon polyps, they can be:

• Bleeding: Sometimes you can see blood in your stool. In some cases, it is occult (meaning you cannot see it) and can cause iron-deficiency anemia (low red blood cell counts).
• Obstruction (blockage): If a polyp is very large and becomes cancer, it can block stool in your bowel (obstruction). Intestinal obstruction (block) can cause nausea, vomiting, bloating, and severe belly pain. If an obstruction is not treated, it can cause perforation (tearing of the wall of your colon). If you have any symptoms of obstruction, call your provider right away.

What causes colon polyps?

You can get colon polyps from environmental (the world around you) and genetic (passed down from your parents) factors. Some things that raise your risk of colon polyps are:

• Diets high in fats and red meats.
• Tobacco use.
• Smoking.
• Obesity.

Polyps are more common as you get older. Talk with your provider if you have a family history of polyps or colon cancer, as this can also increase your risk.

How are polyps diagnosed?

The test most often used is colonoscopy.

Learn more about the tests available for colon cancer screening.

How are polyps linked to colon cancer?

Most colon cancers start as a polyp, but only a very small number of colon polyps become cancer. Talk to your provider about the types of polyps and your risk factors.

What are the types of polyps?

Polyps are either neoplastic (adenoma), meaning they could become cancer, or non-neoplastic (hyperplastic), meaning they will not become cancer. They can also be described by their shape: sessile (flat), pedunculated (having a stalk), and flat or "depressed.” There are ways that your provider can figure out the type of polyp and the need for biopsy.

Non-Neoplastic Polyps

Non-neoplastic polyps do not become cancer. There are many types of non-neoplastic polyps:

• Hyperplastic polyps are the most common colon polyps. Some people with these polyps have hyperplastic polyposis syndrome, making them more at risk for polyps. This rare syndrome is defined by the number of hyperplastic polyps, their size, and where they are found.
• Inflammatory pseudopolyps are not really polyps. They are formed when ulcers in the colon heal, and the mucosa (lining of the colon) looks like a polyp. There can be one or many. Inflammatory pseudopolyps can happen in any form of severe colitis, such as Crohn's disease, ulcerative colitis, and ischemic colitis.

Neoplastic Polyps

Neoplastic polyps can lead to a type of cancer called "carcinoma." These polyps look different than other polyps under a microscope.

• Adenomatous polyps can lead to invasive colon and rectal cancer. There are three types:  villous (most likely to turn to cancer), tubulovillous, and tubular adenoma (least likely to turn to cancer).
  • About 10 to 30% of adenomas are familial, meaning they are caused by genetic variations. Other risks for adenoma are increasing age and a high-fat diet.
  • Adenomas should be taken out since they can lead to cancer.
• Carcinomatous polyps are a type of adenoma that has cancer cells in them. Malignant polyps make up about 5% of adenomas and are often taken out. They are more likely to lead to cancer or to spread to the lymph nodes. Malignant polyps should be taken out when high-risk factors are found, such as invasion of blood vessels or lymphatics, invasion of deeper tissues, involvement of polypectomy margin with cancer, and poor degree of differentiation.
• Serrated polyps may be sessile or pedunculated. There are three types of serrated polyps: hyperplastic polyp, sessile serrated adenoma (SSA), and traditional serrated adenoma (TSA).
  • Hyperplastic polyps are small, sessile lesions and are often less than 5 mm. Hyperplastic polyps are common but are not precursors to cancer.
  • SSAs and TSAs have features of both hyperplastic polyps and adenomatous polyps. SSAs and TSAs are much rarer than hyperplastic polyps. These polyps lead to cancer. They are often treated like adenomas.

What are polyposis syndromes?

Inherited genetic mutations can cause many polyps to grow in your intestinal tract, sometimes starting at a young age. These mutations can raise your risk of colorectal cancer, as well as pancreatic, thyroid, and breast cancer. Some polyposis syndromes are:

• Familial adenomatous polyposis (FAP):The most common polyposis syndrome. FAP comes from a mutation in the APC (adenomatous polyposis coli) gene. People with FAP have hundreds to thousands of adenomatous polyps in their large intestine. Polyps are also found in the stomach and small intestine. If untreated, 100% of people with FAP will develop colon cancer, often before 40 years of age. If you have FAP, you are also more at risk for cancer of the duodenum (first part of the small intestine), stomach, pancreas, thyroid, liver, and brain. You are also at risk for growths in your abdomen (belly) called desmoid tumors. If you have a family member with FAP, you should have genetic testing at 10 to 12 years of age.
• Turcot Syndrome: A genetic condition where there are polyps in your colon that have become colorectal cancer, and a primary brain tumor. There are two types of Turcot syndrome:
  • Turcot syndrome 1(TS1): Colorectal cancer and primary brain tumor caused by a mismatch repair (MMR) mutation.
  • Turcot syndrome 2 (TS2): Colorectal cancer and primary brain tumor caused by APC mutation.

If you have a family history of Turcot syndrome, you should be screened for pre-cancerous colon polyps beginning at age 35. Genetic testing may be useful in individuals with FAP and HNPCC.

• Gardner Syndrome: Comes from APC mutations. This syndrome can cause colonic polyposis, osteomas (noncancerous bone tumors), and dental abnormalities (extra teeth). Osteomas most often affect the mandible (the jawbone). They are only taken out to help symptoms or for cosmetic appearance (how you look), since they are benign (not cancer). People with Gardner Syndrome have the same risk of colorectal cancer as those with FAP. They should talk to a genetic expert about screening.
• Peutz-Jeghers Syndrome: Caused by a change in the STK1 (LKB1) gene. This syndrome can cause a change in color around your mouth, nose, lips, hands, and feet, along with polyps of the stomach, small intestine, and colon. The polyps are found mostly in your small intestine, but can be found in your colon. A colonoscopy should be done at least every 2 to 3 years, even if there are no symptoms of polyps. If there are polyps, a small bowel exam should be done every 1 to 3 years. People with Peutz-Jeghers syndrome are also at higher risk of cancer of the small intestine, pancreas, breast, uterus, ovaries, lung, cervix, or testes.
•  Juvenile Polyposis Syndrome: Caused by changes in PTEN, BMPR1A, or SMAD4 genes. This syndrome can cause many benign hamartomatous (often found in children) polyps in the colon and rectum. The polyps can cause bleeding, intussusception (when bowel slides up into itself, like a telescope), or bowel obstruction (a block in the bowel). There is a higher risk for cancers of the colon, small intestine, and stomach. Colonoscopy should be done at least every 3 years, when symptoms start, or in the early teens (if there are no symptoms).
• Lynch Syndrome (HNPCC or Hereditary Non-Polyposis Colorectal Cancer): Lynch syndrome can lead to colon, breast, endometrial (uterus), gastric, and ovarian cancers.

There are other polyposis syndromes such as Bloom's syndrome, familial tooth agenesis syndrome, MUTYH polyposis, PTEN hamartoma tumor syndromes, neurofibromatosis, Cronkhite-Canada syndrome, hyperplastic polyposis syndrome, and nodular lymphoid hyperplasia. If you are worried about possible genetic conditions that may put you at higher risk of colon polyps and cancers, talk with your provider about genetic counseling and testing.

How are polyps treated? What follow-up do I need?

Polyps are treated by removal (polypectomy) during colonoscopy. Taking out adenomas greatly lowers your risk of developing colon cancer. Polypectomy lowers the risk of colon cancer by up to 80%. The goal of polypectomy is to remove the whole polyp. When one polyp is found, the whole colon should be looked at to see if there are more polyps. Polyps are cut out, and the tissue is burned to seal off the tissue and blood vessels (electrocautery) and stop any bleeding. If the polyps were found with a screening test other than a colonoscopy, you will need to have a colonoscopy to remove the polyps. Bleeding is the most common side effect. Other less common but serious side effects are bowel perforation and electrocautery burn. These can be serious and may need surgical repair.

If polyps can’t be removed during a colonoscopy, you may need surgery. Surgery for polyps and polyposis syndromes should be done by a colorectal surgeon.

If you have a history of neoplastic polyps, you may have a higher risk of colon cancer compared to the average population. It is recommended that you have screening colonoscopies more often.

The U.S. Multi-Society Task Force on Colorectal Cancer has these recommendations for colonoscopy follow-up:

Talk to your provider about any questions you may have about polyps, screening and risk reduction.

To learn about factors that could affect your cancer risk, use the Reduce My Risk tool.