Colorectal Cancer Diagnosis
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 will ask about your personal and family medical history and give 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), then a biopsy to check for cancer cells may be necessary. Often, the abnormal tissue can be removed during a colonoscopy or sigmoidoscopy. A pathologist checks the tissue for cancer cells using a microscope.
Colon and rectal polyps are important, since some may turn into colorectal cancer over time. It is important to recognized that while not every polyp turns to cancer, experts believe that colorectal cancer typically begins as a small non-cancerous polyp. Fortunately, during a colonoscopy, these polyps can be identified and removed or destroyed--thus preventing colorectal cancer. If a polyp is large enough, tissue can be retrieved and sent for biopsy to determine the exact type of polyp.
There are four types of polyps that commonly occur within the colon:
- Inflammatory - Inflammatory polyps are 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 - Hyperplastic polyps are common, usually very small and often found in the rectum. They are considered to be low risk for cancer.
- Tubular adenoma or adenomatous polyp - These are the most common type of polyp and are the ones referred to most often when a doctor speaks of colon or rectal polyps; about 70% of polyps removed are of this type. Adenomas carry a definite cancer risk that rises as the polyp grows larger. Adenomatous polyps usually cause no symptoms, but, if detected early, they can be removed during a 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 - Villous and tuulovillous ademonas account for about 15% of the polyps that are removed. These are the most serious type of polyps with a very high cancer risk as they grow larger. Often, they are sessile (without a stem) making removal more difficult. Smaller ones can be removed in pieces—sometimes over several colonoscopies. Larger sessile villous adenomas may require surgery for complete removal. Follow up depends on the size and completeness of removal.