Colon Polyps and Your Cancer Risk

Polyps in colon, artwork
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Virtually all colon cancer develops from polyps in the colon. Polyps don't always become cancerous, but your risk of developing cancer increases with the number and size of colon polyps you have. A personal or family history of polyps puts you at higher risk for colon cancer as well.

Polyp Types and Cancer Risk

There are several types of polyps. Two are considered to be very low risk: hyperplastic polyps and pseudopolyps. Hyperplastic polyps are fast-growing, but unlikely to become cancerous. Inflammatory pseudopolyps are a symptom of inflammatory bowel conditions, such as Crohn's disease, and are completely benign.

Adenomatous polyps, or adenomas, are higher-risk growths. About two-thirds of the polyps found during colonoscopies are adenomas. This type of polyp can take years to grow into cancer, but should still be removed; after 10 years, about 14 percent may develop into colon cancer. A rare subtype of adenomas, called villous adenomas, are most likely to become cancerous.

Polyp Type Risk for Colon Cancer
Hyperplastic polyps Unlikley
Inflammatory pseudopolyps None (benign)
Adenomatous polyps Higher risk
Villous adenomas Highest risk

The size and number of polyps are also factors in terms of your cancer risk:

  • Approximately 1 percent of polyps with a diameter less than a centimeter are cancerous.
  • If you have more than one polyp or the polyp is bigger than a centimeter, you're considered at higher risk for colon cancer.
  • Up to 50 percent of polyps greater than 2 centimeters (about the diameter of a nickel) are cancerous.

Factors That Increase Your Risk

While colon polyps can happen to anyone, there are certain factors that put you at increased risk for them and, in turn, colon cancer. Family history is key among them.

Family history is a key risk factor for polyps and colon cancer. It may not be the most comfortable conversation to have, but you should find out if your parents, siblings, or children have ever had any colon polyps. If they have, you're no longer in the average-risk category for colon cancer.

In general, if two or more first-degree relatives have had colon polyps, or any first-degree relative discover a colon polyp before age 60, you're considered at higher risk.

Polyps are common and increase with age, which is why colonoscopy is recommend as we grow older.

Other risk factors include:

  • Genetics (some hereditary conditions increase the risk of colon cancer)
  • Ethnicity (African-Americans and people of Ashkenazi Jewish descent are at greater risk)
  • Obesity
  • Smoking
  • Inflammatory bowel conditions

Screening

Recommendations for screening—most frequently via colonoscopy, though other tests are available—vary based on risk.

For those at average risk, the American Cancer Society (ACS) recommends screening begin at age 45 and continue through age 85. The U.S. Multi-Society Task Force on Colorectal Cancer makes further recommendations based on family history.

Generally speaking:

  • If two or more first-degree relatives have had colon polyps, your doctor will recommend that you screen earlier and more frequently than those at average risk—by age 40, or at least 10 years before your youngest relative was diagnosed, whichever comes first.
  • If you have a parent or sibling who has had a polyp, the same higher-risk recommendation applies. For example, if your brother had a polyp removed when he was 45, you should get a colonoscopy when you're 35.

Speak to your doctor about when you should begin screening and how often, as what's appropriate for you.

If polyps are found during a screening, your doctor may suggest you receive a follow-up colonoscopy, depending on your personal risk factors and the type of polyps removed. (Without any polyps, your next colonoscopy would be 10 years later.)

Prevention

Regular screening is the most important step you can take to prevent polyps and colon cancer.

Getting regular physical activity, not smoking, and moderating alcohol intake will provide protective benefits as well.

Consuming antioxidants in the form of tea, leafy greens, and berries—along with healthy fats and high-fiber grains, fruits, and veggies—may also help.

Lastly, watch your folate, vitamin D, and vitamin C intake. Maintaining high levels of these nutrients has been linked to reduced risk of colon cancer in some studies.

When to See the Doctor

Polyps are generally asymptomatic. You are unlikely to know you have them, which is why colonoscopies are important. Be sure to stick with your recommended screening schedule.

Polyps can occasionally become ulcerous (turn into a sore) or bleed. Rarely, they can also cause a feeling of incomplete emptying (called tenesmus) or obstruct the bowel, causing constipation, bloating, vomiting, and other concerns.

Such symptoms always warrant checking with your doctor.

A Word From Verywell

While the possibility of having polyps and them turning into cancer is unsettling, know that the majority of polyps can be removed safely during a colonoscopy. Rarely, surgery may be required for larger polyps. Since it's not always possible to distinguish polyp type during a procedure, doctors will generally remove any polyps they find and send them for biopsy.

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