Colon Cancer Alliance

What is Colorectal Cancer and How Can It Be Prevented?

Diagnosis of Colorectal Cancer

If you have screening test results that suggest cancer or you have symptoms, your doctor must find out whether they are due to cancer or some other cause. Your doctor asks about your personal and family medical history and gives you a physical exam. You may have one or more of the tests described in the Screening section.

If your physical exam and test results do not suggest cancer, your doctor may decide that no further tests are needed and no treatment is necessary. However, your doctor may recommend a schedule for checkups.

If tests show an abnormal area (such as a polyp), a biopsy to check for cancer cells may be necessary. Often, the abnormal tissue can be removed during colonoscopy or sigmoidoscopy. A pathologist checks the tissue for cancer cells using a microscope.

Colon polyps are important, since some may turn into colon cancer over time. While not every colon polyp turns to cancer, it is felt that almost every colon cancer begins as a small non-cancerous polyp. Fortunately, during colonoscopy these polyps can be identified and removed or destroyed--thus preventing a possible colon cancer. If a polyp is large enough, tissue can be retrieved and sent for biopsy to determine the exact type of polyp.

There are 4 types of polyps that commonly occur within the colon:

Inflammatory - Most often found in patients with ulcerative colitis or Crohn's disease. Often called "pseudopolyps" (false polyps), they are not true polyps, but just a reaction to chronic inflammation of the colon wall. They are not the type that turns to cancer. They are usually biopsied to verify type.
Hyperplastic - A common type of polyp which is usually very small and often found in the rectum. They are considered to be low risk for cancer.
Tubular adenoma or adenomatous polyp - This is the most common type of polyp and the one referred to most often when a doctor speaks of colon polyps. About 70% of polyps removed are of this type. Adenomas carry a definite cancer risk which rises as the polyp grows larger. Adenomatous polyps usually cause no symptoms, but if detected early they can be removed during colonoscopy before any cancer cells form. The good news is that polyps grow slowly and may take years to turn into cancer. Patients with a history of adenomatous polyps must be periodically reexamined.
Villous adenoma or tubulovillous adenomas - About 15% of polyps removed are of this type. These are the most serious type of polyp with a very high cancer risk as they grow larger. Often these are sessile and not on a stem making removal more difficult. Smaller ones can be removed in piecemeal fashion--sometimes over several colonoscopies. Larger sessile villous adenomas may require surgery for complete removal. Follow up depends on size and completeness of removal.

Learn more: Staging

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