Colorectal Adenoma (Polyp)

What is a colorectal adenoma?

A colorectal adenoma is a small growth of tissue, commonly called a polyp, that forms on the lining of the colon or rectum. These growths are very common, especially as people get older. While adenomas are benign (non-cancerous) when they first develop, they are considered pre-cancerous because they have the potential to transform into colorectal cancer. This transformation process is slow, often taking 10 years or more, which is why screening colonoscopy is effective at preventing cancer by finding and removing these polyps before they can change.

Do polyps cause symptoms?

Most colorectal adenomas do not cause any symptoms, which is why screening is so important. When symptoms do occur, they can include:

• Rectal bleeding: You might see bright red blood on toilet paper or darker blood mixed with your stool.
• Changes in bowel habits: This can include new constipation or diarrhea that lasts for more than a week.
• Changes in stool color: Stool may appear black or have red streaks.
• Abdominal pain or discomfort.
• Fatigue or weakness: This can be a sign of iron deficiency anemia caused by slow, chronic bleeding from a polyp.

What causes colorectal polyps?

The exact cause of colorectal adenomas is not fully understood, but they develop when there are errors in the way cells grow and divide in the lining of the colon. This leads to the formation of a small clump of cells, or a polyp. Several factors are known to increase your risk of developing polyps:

• Age: The risk of developing polyps increases significantly after age 45.
• Personal or family history: Having a personal history of polyps or colorectal cancer, or a close relative (parent, sibling, or child) with these conditions, increases your risk.
• Genetic syndromes: Certain inherited conditions like Familial Adenomatous Polyposis (FAP) and Lynch Syndrome greatly increase the risk.
• Lifestyle factors: Smoking, heavy alcohol use, obesity, and a diet high in red and processed meats can increase your risk.
• Inflammatory bowel disease: Chronic inflammation from conditions like Crohn's disease or ulcerative colitis increases the risk.

How are polyps found and diagnosed?

The gold standard for detecting and removing colorectal polyps is a colonoscopy. During this procedure, a doctor uses a long, flexible tube with a camera to examine the entire lining of your colon and rectum. If polyps are found, they can usually be removed at the same time using a wire loop (snare) or biopsy forceps passed through the colonoscope. The removed tissue is then sent to a pathologist who examines it under a microscope to determine the type of polyp (e.g., adenoma, serrated polyp) and to check for any cancerous changes.

How are polyps treated?

The primary treatment for colorectal adenomas is removal, a procedure called polypectomy, which is typically performed during a colonoscopy.

• For smaller polyps: These are often removed with biopsy forceps or a wire loop called a snare.
• For larger or flat polyps: Advanced techniques like Endoscopic Mucosal Resection (EMR) or Endoscopic Submucosal Dissection (ESD) may be used. These involve injecting a solution under the polyp to lift it away from the deeper layers of the colon wall before removing it with a snare.
• For polyps with cancer: If a polyp is found to contain invasive cancer after it's removed, further treatment may be needed. If the cancer is confined to the polyp and has no high-risk features, the polypectomy may be sufficient. However, if there are high-risk features, a surgical resection of that segment of the colon is usually recommended to remove any cancer that may have spread to the lymph nodes.

If my polyps are removed, can they come back?
Yes, if you have had adenomas, you are at an increased risk of developing new ones in the future. This is why regular follow-up colonoscopies are so important. The timing of your next colonoscopy will depend on the number, size, and type of polyps that were removed.

Are all polyps pre-cancerous?
No. There are different types of polyps. Adenomatous polyps and serrated polyps are considered pre-cancerous. Other types, like hyperplastic polyps, are very common and usually have a very low risk of becoming cancerous.

• Yang D, Whiteford MH. Management of Malignant Polyps. In: Steele SR, Hull TL, Hyman N, Maykel JA, Read TE, Whitlow CB, eds. The ASCRS Textbook of Colon and Rectal Surgery. 4th ed. Springer; 2022:413-427.
• National Institute of Diabetes and Digestive and Kidney Diseases. Colon Polyps. Published November 2017. Accessed October 12, 2025. https://www.niddk.nih.gov/health-information/digestive-diseases/colon-polyps
• American Cancer Society. Colon Polyps. Revised September 1, 2022. Accessed October 12, 2025. https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/how-diagnosed.html