Colon Polyps

What is a Colon Polyp?

Polyps are benign, fleshy growths (noncancerous tumors or neoplasms) that grow on the lining or inside of the colon (large bowel). They vary in size from less than a quarter of an inch to several inches in diameter. Usually they differ in color and texture from the surrounding normal colon lining. They protrude into the lumen (bowel cavity) and can look like warts or strawberries. Some of them have a stalk like a mushroom. Some patients have multiple polyps in different parts of their colon. Most patients with polyps have no symptoms.

How Common are Polyps?

Colon polyps are very common in adults, especially because the main risk factor for polyps is advancing age. On average, 25% of adults who are 60 years old have one or more polyps. After age 50, the risk of developing polyps doubles every 10 years. Most polyps, and most colon cancers, occur in people with no risk factors and no family history of polyps or cancer.

Are there Different Types of Polyps?

There are two main types of polyps. The most important is the adenomatous polyp. Although most adenomatous polyps are benign, some can turn into cancer over time. Some experts estimate that between 1 in 20 and 1 in 50 adenomatous polyps, if left alone, will become cancers with time. The bigger the adenomatous polyp, the more likely it is to harbor cancer.

The second major type of polyp is the hyperplastic polyp. These can look just like adenomatous polyps through the colonoscope, but they look different when taken out and examined under a microscope. They are always benign and never turn into cancer. Because these two types of polyps look alike, doctors generally remove or sample all polyps found at colonoscopy and then send them for microscopic analysis.

What Causes Polyps and What are the Risk Factors for Developing Polyps?

No one knows exactly what causes polyps, but doctors do recognize several risk factors. The strongest of these is age. After age 50 the risk of having or developing polyps is significant and increases with advancing age. Other risk factors include a personal or family history
of colon polyps or cancer. For better or worse, diet, lifestyle, and medications play a very small or unimportant role in causing or preventing colon polyps and colon cancer. The best method for decreasing one's risk of getting colon cancer is detection and removal of adenomatous polyps.

How Often do I Need a Colonoscopy if I have Polyps?

Your doctor will recommend an appropriate time to repeat your colonoscopy. The decision is based on several factors including the type, size, and number of polyps found, the adequacy of the colon cleansing, your age, general health, and results of prior colon tests, and your personal and family history. Common intervals between colonoscopies are three to five years but can be as short as a few months or as long as 10 years.

Are there Other Tests, Besides Colonoscopy, to Look for Polyps?

There are other tests designed to detect polyps or cancer of the colon, however none is as accurate as colonoscopy. Stool tests for blood, x-rays (such as barium enema), and CT scans with "virtual colonoscopy" software may suggest the presence of polyps or cancer. However, only colonoscopy allows biopsy of these growths and/or their total removal. At the present time, these other tests miss polyps that are later detected by colonoscopy. X-rays and CT scans require exposure to radiation, which can be potentially harmful. Data from the National Polyp Study shows that removing adenomatous polyps prevents the development of colon cancer. This is a radical difference from other cancer screening tests (such as mammograms, Pap smears, and prostate tests) that allow early detection of cancer but have no capability to prevent the development of the cancer being screened for. For these reasons, colonoscopy is the current "gold standard" for detecting, diagnosing, and removing colon polyps.

In Summary

  • Colon polyps are common
  • They affect men and women equally
  • They are responsible for more than 150,000 cases of colorectal cancer in the USA each year
  • They can be managed best via colonoscopy