Colorectal Polyps
Growths on the lining of the colon or rectum
Quick Facts
- Type: Digestive (gastrointestinal) growth
- Location: Colon and rectum
- Key concern: Some can become cancerous over years
- Detection: Colonoscopy screening
Overview
A colorectal polyp is a small clump of cells that forms on the inner lining of the large intestine, which includes the colon and the rectum. Polyps are very common, especially with increasing age, and most are harmless. However, certain types of polyps can slowly grow and, over many years, develop into colorectal cancer. Because this process is gradual, finding and removing polyps before they become cancerous is one of the most effective ways to prevent colorectal cancer.
Polyps come in different shapes. Some are flat, while others rise on a stalk like a mushroom. They also differ in their cell type. Adenomatous polyps (adenomas) carry the greatest cancer risk, while small hyperplastic polyps rarely become cancerous. Most polyps cause no symptoms at all, which is why screening is so important: they are often found during routine examinations in people who feel completely well.
Symptoms
Most colorectal polyps cause no symptoms and are discovered during screening. When symptoms do occur, they may include:
- Rectal bleeding: Bright red blood on toilet paper or in the stool.
- Blood in the stool, which can make stool look darker than usual.
- Change in bowel habits lasting more than a week, such as constipation or diarrhea.
- Iron-deficiency anemia: Slow, hidden bleeding can lower iron levels, causing tiredness and pale skin.
- Abdominal discomfort in some cases, particularly with larger polyps.
Because these symptoms overlap with many other conditions, including hemorrhoids and colorectal cancer, any rectal bleeding or persistent change in bowel habits should be evaluated.
Causes
Polyps form when cells in the lining of the colon or rectum grow and divide more than they should. The exact trigger is often unknown, but genetic changes in these cells drive the abnormal growth. Several factors influence how likely polyps are to form:
- Age: Polyps become more common after age 45 to 50.
- Inherited conditions: Rare genetic syndromes, such as familial adenomatous polyposis and Lynch syndrome, cause many polyps and a high cancer risk.
- Lifestyle factors: A diet high in red and processed meat and low in fiber, obesity, smoking, and heavy alcohol use are all associated with more polyps.
Most polyps are not inherited and develop sporadically as a person ages. The same factors that increase polyps also increase the long-term risk of colorectal cancer.
Risk Factors
- Age 45 or older
- A personal or family history of polyps or colorectal cancer
- Inherited polyp syndromes such as familial adenomatous polyposis or Lynch syndrome
- Inflammatory bowel disease, including ulcerative colitis and Crohn disease
- Type 2 diabetes that is not well controlled
- Obesity, smoking, heavy alcohol use, and a diet low in fiber and high in red or processed meat
Diagnosis
Colorectal polyps are usually found through screening tests, often before any symptoms develop:
- Colonoscopy: The most thorough test, using a flexible camera to view the entire colon and rectum; polyps can be removed during the same procedure.
- Stool tests: Tests that detect hidden blood or abnormal DNA in the stool; an abnormal result is followed by colonoscopy.
- CT colonography: A specialized scan that creates images of the colon when colonoscopy is not suitable.
- Biopsy: Removed polyps are examined under a microscope to determine their type and whether any cancer cells are present.
Treatment
The standard treatment is removal, which is usually simple and effective:
- Polypectomy: Most polyps are removed painlessly during colonoscopy using a wire loop or small instruments.
- Endoscopic resection: Larger or flatter polyps may need specialized techniques to remove them in pieces or as a whole.
- Surgery: Rarely needed, and reserved for very large polyps, those that cannot be removed endoscopically, or inherited syndromes with very many polyps.
After removal, the polyp is examined under a microscope. Based on the number, size, and type of polyps found, your doctor will recommend when to have your next colonoscopy, since people who have had adenomas need closer follow-up.
Prevention
- Follow recommended colorectal cancer screening, usually starting around age 45 or earlier if you have risk factors
- Eat plenty of fruits, vegetables, and whole grains for fiber
- Limit red and processed meats
- Maintain a healthy weight and stay physically active
- Avoid smoking and limit alcohol
- Tell your doctor about any family history of polyps or colorectal cancer so screening can begin at the right age
When to See a Doctor
See a doctor if you notice rectal bleeding, blood in your stool, a lasting change in bowel habits, or unexplained tiredness that could reflect anemia. Also talk with your doctor about screening if you:
- Are 45 or older and have never been screened
- Have a family history of colorectal polyps or cancer
- Have inflammatory bowel disease
Screening can find and remove polyps before they ever cause symptoms or become cancerous.
Frequently Asked Questions
Are colorectal polyps cancer?
No, most polyps are not cancer. However, certain types, especially adenomas, can slowly turn into colorectal cancer over many years, which is why they are removed when found.
Do colorectal polyps cause symptoms?
Usually not. Most polyps cause no symptoms and are found during screening. When symptoms occur, they may include rectal bleeding, blood in the stool, or a change in bowel habits, all of which should be checked.
How are polyps removed?
Most are removed during a colonoscopy using a small wire loop or instrument, a quick and generally painless procedure called a polypectomy. Surgery is rarely needed and is reserved for unusually large polyps or certain inherited conditions.
How often should I be screened after polyps are found?
It depends on the number, size, and type of polyps removed. People who have had adenomas usually need more frequent colonoscopies, and your doctor will recommend a specific follow-up interval based on your results.
Can I lower my risk of developing polyps?
Yes. Eating a high-fiber diet, limiting red and processed meat, staying active, maintaining a healthy weight, not smoking, and limiting alcohol all help. Regular screening also removes polyps before they can become a problem.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Colon Polyps.
- Mayo Clinic. Colon polyps — Symptoms and causes.
- American Cancer Society. Colorectal cancer screening.
- MedlinePlus, U.S. National Library of Medicine. Colorectal polyps.