Colon Polyps and Your Cancer Risk

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. In addition, a personal or family history of polyps puts you at higher risk for colon cancer.

This article explains colon polyps, how they impact your cancer risk, and more.

Polyp Types and Cancer Risk

There are several types of polyps. Some are lower risk than others. In addition, your risk of cancer increases if you have more or bigger polyps.

Low Risk Types

Two types of polyps are very low risk:

• Hyperplastic polyps
• Pseudopolyps

Hyperplastic polyps are small polyps found at the end of the colon and rectum. They are fast-growing but unlikely to become cancerous.

Inflammatory pseudopolyps are a symptom of inflammatory bowel conditions, such as ulcerative colitis or Crohn's disease. These types of polyps are benign (noncancerous).

Higher Risk Types

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—after 10 years, about 14% may develop into colon cancer. Therefore, they should be removed.

A rare subtype of adenomas, called villous adenomas, is most likely to become cancerous.

Number and Size

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

• Approximately 1% of polyps with a diameter less than 1 centimeter (cm) are cancerous.
• More than one polyp or a polyp that is 1 cm or bigger places you at higher risk for colon cancer.
• Up to 50% of polyps greater than 2 cm (about the diameter of a nickel) are cancerous.

A polyp is considered an advanced colon polyp (a high-risk lesion) if it is 1 cm or larger, has a villous component, or has high-grade dysplasia (highly abnormal cells that could turn into cancer).

Factors That Increase Your Risk

While colon polyps can happen to anyone, certain factors put you at increased risk for them and, in turn, colon cancer.

Risk factors include:

• Family history
• Older age
• Genetics (some hereditary conditions increase the risk of colon cancer)
• Race and ethnicity (African Americans and people of Ashkenazi Jewish descent are at greater risk)
• Obesity
• Smoking
• Inflammatory bowel conditions

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 advanced colon polyps. If they have, you're no longer in the average-risk category for colon cancer.

Polyps are increasingly common as you age, which is why experts recommend screening with a colonoscopy as you grow older.

Screening

Though other tests are available, colonoscopy is most frequently used to screen for colon cancer. Recommendations for screening vary based on risk.

Who Should Be Screened?

For those at average risk, the American College of Gastroenterology (ACG) recommends screening begin at age 45 and continue through at least age 75.

However, if you have a family history of colon polyps, the ACG recommends screening earlier, including:

• If two or more first-degree relatives have had advanced colon polyps, begin screening with a colonoscopy at age 40 or 10 years before the youngest affected relative, whichever is earlier.
• The same higher-risk recommendation applies if a parent or sibling has had an advanced polyp. 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 healthcare provider about when you should begin screening and how often.

How Often to Screen

For people without any polyps or family history, colonoscopies are typically recommended every 10 years.

However, suppose your doctor finds polyps during a screening. In that case, your healthcare provider may suggest you receive a follow-up colonoscopy earlier than that, depending on your risk factors and the type of polyps removed.

If your doctor finds no polyps, but you have first-degree relatives who had advanced polyps, your next colonoscopy would typically be five years later.

Prevention

Regular screening is the most critical step you can take to prevent polyps and colon cancer. In addition, some lifestyle factors can lower your risk, including:

• Getting regular physical activity
• Not smoking
• Moderating alcohol intake
• Eating a healthy and varied diet

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

Lastly, watch your folate, calcium, and vitamin D intake. These natural approaches have been linked to a reduced risk of colon cancer in some studies.

When to See a Healthcare Provider

Polyps are generally asymptomatic, which means you are unlikely to know you have them. That is why colonoscopies are essential. So, be sure to stick with your recommended screening schedule.

When polyps produce symptoms, they may include:

• Bleeding from the rectum
• A feeling of incomplete emptying (called tenesmus)
• Constipation
• Bloating
• Vomiting

Such symptoms always warrant checking with your healthcare provider.

Summary

Having colon polyps increases your risk of colon cancer. However, not all polyps hold the same level of risk—some types are always benign, while others may develop into cancer over time. The more polyps you have, and the bigger they are, the greater your risk.

Colon cancer screening begins at age 45; however, screening should start earlier if you have family history risk factors. Since polyps are often asymptomatic, screening is essential for catching them early.

A Word From Verywell

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