Overview

A colon polyp is a small clump of cells that forms on the lining of the colon. Most colon polyps are harmless. But over time, some colon polyps can develop into colon cancer. Colon cancer can be fatal when found in its later stages.

Anyone can develop colon polyps. You're at higher risk if you are 50 or older, are overweight or are a smoker. You're also at higher risk if you have a personal or family history of colon polyps or colon cancer.

Colon polyps don't usually cause symptoms. It's important to have regular screening tests because colon polyps found in the early stages can usually be removed safely and completely. The best prevention for colon cancer is regular screening for and removal of polyps.

Symptoms

Most people with colon polyps do not have any symptoms. You might not know you have a polyp until your health care provider finds it during an exam of your colon.

However, some people with colon polyps may have:

  • Change in bowel habits. Constipation or diarrhea that lasts longer than a week may mean the presence of a larger colon polyp or cancer. However, several other conditions also can cause changes in bowel habits.
  • Change in stool color. Blood can show up as red streaks in your stool or make stool appear black. A change in color also may be caused by certain foods, medicines or dietary supplements.
  • Iron deficiency anemia. Bleeding from polyps can happen slowly over time, without visible blood in your stool. Chronic bleeding may lead to iron deficiency anemia, which can make you feel tired and short of breath.
  • Pain. A large colon polyp can block part of your bowel, leading to crampy abdominal pain.
  • Rectal bleeding. This can be a sign of colon polyps or cancer or other conditions, such as hemorrhoids or minor tears of the anus.

When to see a doctor

See your health care provider if you experience:

  • Abdominal pain.
  • Blood in your stool.
  • A change in your bowel habits that lasts longer than a week.

You should be screened regularly for polyps if:

  • You're age 50 or older.
  • You have risk factors, such as a family history of colon cancer. Some high-risk individuals should begin regular screening much earlier than age 50.

Causes

Healthy cells grow and divide in an orderly way. Changes in certain genes can cause cells to continue dividing even when new cells aren't needed. In the colon and rectum, this continued growth of cells can cause polyps to form. Polyps can grow anywhere in the large intestine.

There are two main categories of polyps, nonneoplastic and neoplastic. Nonneoplastic polyps typically do not become cancerous. Neoplastic polyps include adenomas and serrated types. Adenomas are the most likely to turn into cancer if given enough time to grow. Serrated polyps also may become cancerous, depending on their size and location. In general for neoplastic polyps, the larger the polyp, the greater the risk of cancer.

Risk factors

Factors that might cause colon polyps or cancer include:

  • Age. Most people with colon polyps are 50 or older.
  • Having inflammatory intestinal conditions. Ulcerative colitis or Crohn's disease of the colon increase your overall risk of colon cancer, although the polyps themselves are not a significant threat.
  • Family history. You're more likely to get colon polyps or cancer if you have a parent, sibling or child with them. If many family members have them, your risk is even greater. In some people, this connection isn't hereditary.
  • Smoking and excess alcohol use. Studies show that people who have three or more alcoholic drinks a day have an increased risk of getting colon polyps. Alcohol intake combined with smoking also appears to increase the risk.
  • Obesity, lack of exercise and fat intake. You're at a higher risk if you are overweight, don't exercise regularly and lack a healthy diet.
  • Race. Black Americans have a higher risk of developing colon cancer.

Hereditary polyp disorders

Rarely, people inherit genetic irregularities that cause colon polyps to form. If you have one of these genes, you are at a much higher risk of developing colon cancer. Screening and early detection can help prevent the growth or spread of these cancers.

Hereditary disorders that cause colon polyps include:

  • Lynch syndrome, also called hereditary nonpolyposis colorectal cancer. People with Lynch syndrome tend to develop relatively few colon polyps, but those polyps can quickly become cancerous. Lynch syndrome is the most common form of inherited colon cancer and also is associated with tumors in other parts of the abdomen.
  • Familial adenomatous polyposis (FAP), a rare disorder that causes hundreds or even thousands of polyps to develop in the lining of your colon beginning during your teenage years. If the polyps aren't treated, your risk of developing colon cancer is nearly 100%, usually before age 40. Genetic testing can help determine your risk of FAP.
  • Gardner syndrome, a variant of FAP that causes polyps to develop throughout your colon and small intestine. You also may develop noncancerous tumors in other parts of your body, including your skin, bones and abdomen.
  • MUTYH-associated polyposis (MAP), a condition similar to FAP that is caused by changes in the MYH gene. People with MAP often develop multiple adenomatous polyps and colon cancer at a young age. Genetic testing can help determine your risk of MAP.
  • Peutz-Jeghers syndrome, a condition that usually begins with freckles developing all over the body, including the lips, gums and feet. Then noncancerous polyps develop throughout the intestines. These polyps may become cancerous, so people with this condition have a higher risk of colon cancer.
  • Serrated polyposis syndrome, a condition that leads to multiple serrated adenomatous polyps in the upper part of the colon. These polyps may become cancerous. They need to be watched and possibly removed.

Complications

Some colon polyps may become cancerous. The earlier polyps are removed, the less likely it is that they will become cancerous.

Prevention

You can greatly reduce your risk of colon polyps and colorectal cancer by having regular screenings. Certain lifestyle changes also can help:

  • Adopt healthy habits. Include plenty of fruits, vegetables and whole grains in your diet and reduce your fat intake. Limit alcohol and quit all tobacco use. Stay physically active and maintain a healthy body weight.
  • Talk to your health care provider about calcium and vitamin D. Studies have shown that increasing the intake of calcium may help prevent the return of colon adenomas. But it isn't clear whether calcium has any protective benefits against colon cancer. Other studies have shown that vitamin D may protect against colorectal cancer.
  • Consider your options if you're at high risk. If you have a family history of colon polyps, consider having genetic counseling. If you've been diagnosed with a hereditary disorder that causes colon polyps, you'll need regular colonoscopies starting in young adulthood.
By Mayo Clinic Staff