A colon polyp is a small clump of cells that forms on the lining of the colon. Most colon polyps are harmless, but they can become cancerous, especially those that grow larger over time.
There are two primary categories of colon polyps:
- Neoplastic and non-neoplastic – It is uncommon for non-neoplastic polyp types to develop into colon cancer, and even neoplastic types are often found to be non-cancerous.
- Adenomatous or villous adenomas – Approximately two-thirds of all polyps found in the colon are determined to be adenoma, meaning the polyp is not definitively cancerous but there is an increased risk of being so.
Anyone can develop colon polyps. People are at higher risk if they are overweight, smoke, drink alcohol in excessive amounts, or have a family history of colon polyps or colon cancer. Polyps are also more likely to occur as we age so all adults over 45 should be regularly checked for the presence of tissue formations. Those with a family history of colon cancer should start screening earlier.
Because most people with colon polyps do not experience symptoms, it is difficult to determine if someone has colon polyps without looking inside the colon. That is why regular screening tests, such as a colonoscopy, are very important. Small polyps are particularly unlikely to present symptoms, although the following could occur:
- Rectal bleeding
- Mucus discharge
- Abdominal pain/cramps
- Changes in stool, most commonly color
- Change in bowel habits lasting over a week
- Iron deficiency anemia
Failure to regularly screen for colon polyps can lead to a delayed diagnosis of colon cancer. Most polyps are found during routine procedures like a colonoscopy or sigmoidoscopy. If polyps are found, the doctor will extract the tissues and send them to a lab for testing to determine if they have the potential to become cancerous. Follow-up screening recommendations are generally:
- 5-10 years for 1-2 small adenomas (non-cancerous growth)
- 3-5 years for 3-4 adenomas
- Within 3 years for 5-10 adenomas, adenomas larger than 10 millimeters, or certain types of adenomas
- Within 6 months for multiple adenomas, a very large adenoma, or an adenoma that had to be removed in pieces
Colon polyps found in the early stages can usually be removed safely and completely, likely during the bowel examination. If polyps are too large to be removed safely during screening, minimally invasive surgery will be performed. Some types of colon polyps are more likely to become cancerous. The pathologist who analyzes the tissue samples will determine if they are potentially cancerous.