Colon Cancer: Patient Education

Cancer Facts

According to the American Cancer Society, colon cancer death rates have been declining over the past 20 years, largely due to early detection and improved treatments.

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Your colon is part of your digestive system, also called your gastrointestinal (GI) tract. The organs in your digestive system break down and absorb the food you eat and convert it into products your body can use to stay healthy. Your GI tract, in particular your colon, eliminates the products your body cannot use.

Colon cancer is a group of malignant cells that starts in your large intestine (colon). The growing tumor can affect the function of your colon as well as spread (metastasize) to other parts of your body.

Cancer of the colon and rectum are often referred in combination as colorectal cancer. Excluding skin cancers, colorectal cancer is the third most common cause of cancer death in the United States today. But when found early, it is a highly treatable disease. (For more information about cancer of the rectum, see Rectal Cancer Care.)

How Does Colon Cancer Begin?

Colon cancer generally begins as a non-cancerous (benign) polyp growing on the inner lining of your colon. Your colon is comprised of several layers of muscle.

Cancer comes from a polyp, a small benign growth, which is easily removed through colonoscopy. Polyp-to-cancer growth is a slow process. It takes 10 years or more, in some instances, for the cancer to develop. So there is a long window of opportunity with any patient to go in and change history for that patient — to remove that polyp long before that cancer happens.

Some tests, such as colonoscopy, can find polyps before they become cancer, and most people who have polyps removed never get colon cancer. If a test reveals you have colon cancer, early detection means you have a good chance at beating the disease.

What Is a Polyp?

  • A polyp is a tumor.
  • Some polyps remain benign while others become cancerous (malignant).
  • The likelihood of your polyp becoming cancerous depends on the kind of polyp it is.

There are three kinds of polyps:

  • Adenomatous polyps (adenomas) – precancerous polyps
  • Hyperplastic polyps – usually benign, but may become precancerous, especially if in the ascending colon
  • Inflammatory polyps – generally benign

How Do You Find Polyps?

Most polyps are easily detectable with a colonoscopy, the gold standard for diagnosing polyps. Polyps create a small bump or lump on the wall of your colon.

However, about 10 percent of polyps are flat and are more difficult to detect. These flat polyps have a higher chance of becoming cancerous.

How Do Polyps Lead to Cancer?

  • Polyps can remain benign for a long time. It can often take years for cancer to develop, and even then, colon cancer can be slow growing.
  • Cancerous cells generally begin on the inside layers and grow out through the various layers.
  • How deeply your cancer invades these layers may affect the kind of treatment you’ll have.
  • If left untreated, your colon cancer can spread into your bloodstream or your lymph system, where it can easily spread (metastasize) throughout your body, starting new tumors in new locations.

Because precancerous polyps are potentially life threatening, your GI Cancer Team recommends removing them to prevent colon cancer.

How Often Should I Get Checked for Colon Cancer?

The American College of Gastroenterology and the American Cancer Society recommend screening beginning at age 50.

What About Genetics?

The precise cause of all colon cancers is not known. While most cases of colon cancer are sporadic, some are inherited or have a genetic basis. Find out more.

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