What Is a Polyp?
A polyp is a growth that occurs on the lining of your large intestine that, left unchecked, can become cancer, especially if colon cancer runs in your family.
What is a polyp?
Colon polyps are tissue growths on the wall of your large intestine. They are very common.
Some types of polyps could become malignant. Based on their size, number, and anatomy, they can be an indicator of future potential for colon cancer, especially if it runs in your family.
They affect about 20 to 30 percent of American adults. Polyps can grow flat against the lining of your colon or on stalks like mushrooms. They can grow on any part of your colon but most often occur on the left side.
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In one study of cancerous polyps in 700 patients, more than 900 polyps were found. Just over 50 of the polyps were cancerous.
The majority of polyps do not become malignant, but having them removed may reduce your future risk for colorectal cancer.
Symptoms of colon polyps
Polyps usually do not cause symptoms. Some people, however, may experience rectal bleeding, which can also be a sign of hemorrhoids or a tear in your anus. Other symptoms include:
- Change in stool color
- Change in bowel habits
- Pain, nausea, or vomiting
- Iron deficiency anemia (do to bleeding from your polyps)
Types of polyps
There are many types of polyps, some having the potential to become cancer, while others don’t. Two of the most common types of polyps are hyperplastic and adenomatous.
Hyperplastic polyps are small and likely won’t become cancer.
Adenomas are common. Large adenomas may develop into cancer over time. Most colorectal cancers grow from a polyp that has been present for 5 to 15 years.
The exact risk of an adenoma turning into cancer is difficult to predict, although studies have set the risk as about 1 in 12 after 10 years, and 1 in 4 after about 20 years. Risk seems to vary based on the size of the adenoma and its exact subtype, some of which are more prone to develop into cancer than others.
Polyps can also occur because of polyposis syndromes, a group of hereditary conditions. They are rare and usually occur in young people. They often cause multiple polyps that have a high chance of turning into cancer.
Adenomas are considered the precursor to colorectal cancer and rarely occur in people under age 49, which is why people are urged to start having colonoscopies by age 45.
What causes polyps?
Colonic polyps are caused by an abnormal production of cells. The lining of the bowel constantly renews itself, and chronic inflammation or a faulty gene can cause the cells in the bowel lining to grow more quickly.
Polyps and colorectal cancer develop from genetic mutations or other chemical changes, causing inactivation or promotion of genes known as tumor suppressors or tumor promoters.
Polyps are typically detected during a colonoscopy, in which a long, thin, flexible tube with a camera attached is used to examine your colon walls. The doctor leading the colonoscopy will remove any polyps during the procedure, with an attachment to the tube. The tissue can later be examined in the lab for signs of malignancy.
At least 30 percent of patients will develop new polyps, which is why follow-up colonoscopies are important. Follow-up usually occurs 3 to 5 years after polyp removal.
Some people develop just one polyp, but it’s common to develop two or more. It’s uncommon to have more than five.
What you can do
People with an average risk for colon cancer should start having colonoscopies at age 45, then follow-up colonoscopies every 10 years.
If you have a parent, sibling, or child who was diagnosed with colorectal cancer, your risk is two to four times higher than the risk for someone without that history, the American Cancer Society reports. Your doctor may recommend that you have a colonoscopy starting at age 40, or 10 years before the age that an immediate family member was diagnosed with cancer.
People ages 76 to 85 do not need regular screening, and men and women older than 85 do not need any screening. Know your risks for colon cancer ahead of time.
Prevention of colon polyps is a matter of eating more fruits and vegetables and losing weight if you’re overweight. Some research suggests that getting more calcium and vitamin D may lower your risk of developing polyps.
Research also suggests that avoiding fatty food, red meat, and processed meat such as hot dogs and lunchmeats can help prevent colon polyps. Polyps are more common in industrial countries, suggesting that lifestyle and environment may be a contributor.
Risk factors include a high-fat, high red meat diet, lack of fiber, cigarette smoking, and obesity.
March 02, 2023
Christopher Nystuen, MD, MBA