Colon polyps are small growths that form on the inner lining of the large intestine. They’re extremely common, especially as you age: screening data shows that more than half of adults in their early 50s have at least one adenomatous polyp, and that number climbs to roughly 64% by age 60 to 64. Most polyps are harmless and cause no symptoms, but certain types can slowly develop into colorectal cancer over years if left in place. That’s the entire reason colonoscopy screening exists: to find and remove these growths before they become dangerous.
Types of Colon Polyps
Not all polyps carry the same risk. The type matters far more than the mere presence of a polyp, and a pathologist determines the type by examining the removed tissue under a microscope.
Adenomatous polyps (adenomas) are the most clinically significant. These are the polyps that can progress to cancer through a well-understood chain of genetic changes. About 80% of colorectal cancers begin with a mutation in a gene called APC, which normally keeps cell growth in check. Over time, additional mutations accumulate, gradually transforming normal tissue into a benign polyp, then a more abnormal polyp, and eventually a cancer. This process typically takes 10 to 15 years, which is why regular screening is so effective at prevention.
Sessile serrated polyps are flat, saw-toothed growths that sit flush against the colon wall. They were once lumped in with harmless polyps but are now recognized as a separate pathway to cancer. Because they’re flat and often covered in mucus, they can be harder to spot during a colonoscopy. They tend to appear more frequently in the right side of the colon.
Hyperplastic polyps are the most common type and generally considered benign. Small hyperplastic polyps found in the lower part of the colon carry very little cancer risk. However, larger hyperplastic polyps or those found higher in the colon sometimes warrant closer follow-up.
Why Most Polyps Go Unnoticed
Most people with colon polyps have no symptoms at all. The growths are typically too small to cause problems, and the colon lining doesn’t have the same pain-sensing nerves as your skin. This is why screening is so critical: you can’t rely on feeling something wrong.
When polyps do cause symptoms, it’s usually because they’ve grown large enough to bleed or partially block the intestine. Signs to watch for include:
- Changes in stool color. Blood can appear as red streaks or make stool look black.
- Rectal bleeding. Visible blood on toilet paper or in the bowl.
- Persistent changes in bowel habits. Constipation or diarrhea lasting more than a week.
- Iron deficiency anemia. Polyps can bleed slowly over months, draining your iron stores without any visible blood in the stool. This often shows up as unexplained fatigue or shortness of breath.
- Cramping or abdominal pain. A large polyp can partially obstruct the bowel.
Who Gets Colon Polyps
Age is the single biggest factor. Polyps are relatively uncommon before 40, with about a third of people in the 40 to 44 age range having adenomatous polyps on screening. By the late 50s, that figure exceeds 60%. This steep climb is why the U.S. Preventive Services Task Force lowered the recommended screening age to 45 in 2021.
Family history also plays a major role. If a first-degree relative (parent, sibling, or child) had colorectal polyps or cancer, your own risk increases significantly, and screening may need to start earlier. Inherited conditions like familial adenomatous polyposis, which causes hundreds or thousands of polyps to develop in the teens and twenties, and Lynch syndrome, which raises the risk of several cancers, require more aggressive surveillance.
Lifestyle factors contribute as well. Smoking, heavy alcohol use, obesity, a diet high in red and processed meat, and a sedentary lifestyle are all linked to higher polyp rates. These are also some of the few things you can actually change to lower your risk.
How Polyps Are Found
Colonoscopy remains the gold standard for detecting polyps because it allows a doctor to both see and remove growths in the same procedure. A thin, flexible camera is threaded through the entire colon, giving a direct view of the lining.
For people who can’t or don’t want a colonoscopy, stool-based tests offer an alternative. The fecal immunochemical test (FIT) checks for microscopic blood in your stool, which can signal the presence of polyps or cancer. However, its sensitivity for catching advanced growths is only about 25%, meaning it misses a significant number of dangerous polyps. A positive FIT result still requires a follow-up colonoscopy. Stool DNA tests combine blood detection with genetic markers and are somewhat more sensitive, but they also require colonoscopy to confirm and remove anything they flag.
How Polyps Are Removed
Most polyps are removed during the same colonoscopy in which they’re found, a procedure called polypectomy. You’re already sedated, and the removal itself adds little time or discomfort. The technique depends on the polyp’s size and shape.
Small polyps (under about 10 mm) are typically removed with a cold snare, a tiny wire loop that slices the polyp off at its base without using electrical current. It’s quick, safe, and effective for the majority of polyps found during routine screening.
Larger polyps (20 mm or bigger) require more involved techniques. Endoscopic mucosal resection, or EMR, involves injecting fluid beneath the polyp to lift it away from the colon wall, then removing it with a snare, sometimes in pieces. In Western countries, EMR is the preferred approach for large flat polyps, with recurrence rates between 5% and 20%. Endoscopic submucosal dissection, or ESD, is a more precise technique that removes the entire polyp in one piece by carefully cutting the tissue layer beneath it. This allows a pathologist to evaluate the complete specimen, which is especially important if there’s any suspicion the polyp contains early cancer. ESD has lower recurrence rates but is more technically demanding and carries slightly higher complication risk.
After removal, the polyp tissue is sent to a lab for analysis. The results determine your follow-up schedule. A single small adenoma might mean a repeat colonoscopy in 7 to 10 years, while multiple large adenomas or serrated polyps could mean coming back in just 1 to 3 years.
Can You Prevent Polyps?
There’s no guaranteed way to prevent polyps, but certain habits are consistently associated with lower risk. Regular physical activity, maintaining a healthy weight, eating a diet rich in fruits, vegetables, and fiber, limiting red and processed meat, avoiding smoking, and keeping alcohol intake moderate all appear protective.
You may have heard that aspirin, calcium, or vitamin D supplements can prevent polyps. The evidence here is disappointing. A randomized controlled trial that gave participants a daily combination of low-dose aspirin, calcium carbonate, and vitamin D for three years found no difference in adenoma recurrence compared to placebo. The one potentially interesting finding was that nonsmokers appeared to benefit more than smokers, but the overall result was clearly negative. At this point, no supplement has been proven to reliably prevent polyps from forming or returning.
The most effective form of prevention remains screening itself. Removing polyps before they turn cancerous is estimated to prevent the majority of colorectal cancers. If you’re 45 or older with average risk, getting screened on schedule is the single most impactful step you can take.