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 colorectal cancer. Colorectal cancer can be deadly when found in its later stages.
Anyone can develop colon polyps, and your risk increases as you age. Your risk for colorectal cancer also is higher if you are overweight, smoke, have a personal history of colon polyps, or a family history of advanced colon polyps or colorectal cancer.
Colon polyps don't usually cause symptoms. It's important to have regular screening tests because colon polyps found early can usually be removed safely and completely. The best prevention for colorectal cancer is regular screening.
Symptoms
Most people with colon polyps do not have any symptoms. Colon polyps are often found as a part of routine colorectal cancer screening.
Symptoms that should prompt an appointment with a healthcare professional include:
- 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 the 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 the stool. Chronic bleeding may lead to iron deficiency anemia, which can cause tiredness and shortness of breath.
- Pain. A large colon polyp or cancer can block part of the bowel, leading to cramping and belly 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 a healthcare professional if you experience:
- Belly pain.
- Blood in the stool.
- A change in bowel habits that lasts longer than a week.
- Losing weight without trying.
You should be screened regularly for colorectal cancer if:
- You're age 45 or older.
- You may need to start screening sooner than age 45 depending upon your medical conditions and family history.
Causes
Healthy cells grow and divide in an orderly way. Changes in certain cells can lead to continued 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 lesions. Most cases of colorectal cancer arise from an adenoma that has been present for a long time. However, serrated lesions also can become cancerous. In general for neoplastic polyps, the larger the polyp, the greater the risk of cancer.
Risk factors
Factors that might increase the risk of colon polyps or cancer include:
- Age. Most people with colon polyps are 45 or older.
- Having certain intestinal conditions. Having inflammatory bowel disease, such as ulcerative colitis or Crohn's disease, increases the overall risk of colorectal cancer.
- Family history. Having a parent, sibling or child with advanced colon polyps (polyps 10 mm in size or larger, for example) increases the risk of getting them. If many family members have them, the 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.
- Having diabetes. Diabetes increases polyp risk by 50% among all age groups.
- Obesity, lack of exercise and an unhealthy diet. The risk of colon polyps increases for people who are overweight, don't exercise regularly and lack a healthy diet.
- Race. Black Americans have a higher risk of developing colorectal cancer.
Polyp syndromes
Hereditary disorders are conditions passed down from parents. Rarely, people inherit genetic variants that cause colon polyps to form and increase the risk of developing colorectal cancer. Screening and early detection can help prevent the growth or spread of these cancers.
Conditions that cause colon polyps include:
- Lynch syndrome, also called hereditary nonpolyposis colorectal cancer. People with Lynch syndrome may form 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 the colon during the teenage years. If the polyps aren't treated, the risk of developing colon cancer is nearly 100%, usually before age 40. Genetic testing can help determine the risk of FAP.
- MUTYH-associated polyposis (MAP), a condition similar to FAP that is caused by changes in the MUTYH gene. People with MAP often develop multiple adenomatous polyps and colon cancer at a young age. Genetic testing can help determine the 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.
- Juvenile polyposis syndrome (JPS), an inherited condition that is most common in children ages 1 to 7, though it sometimes happens in adults. Juvenile polyps are often single, but if there are multiple polyps the risk of cancer increases.
- Serrated polyposis syndrome is most often a condition that is not inherited but defined based upon polyp history. This syndrome is considered for individuals with multiple serrated lesions. As these polyps may become cancerous, they need to be removed, and colonoscopy is done more often.
Complications
Some colon polyps may become cancerous. The earlier polyps are removed, the less likely it is that they will become cancerous.
Prevention
The risk of colon polyps and colorectal cancer may be greatly reduced 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.
- Consider your options if you're at high risk. If you have a family history of colon polyps, talk to a healthcare professional. If you have a personal history of 10 or more neoplastic polyps, consider having genetic counseling. Referral to a genetic counselor also may be considered depending upon your family history. If you've been diagnosed with a hereditary disorder that causes colon polyps, you'll need regular colonoscopies starting in young adulthood.