Diagnostic procedures for colorectal cancer
In addition to a complete medical history and physical examination, diagnostic procedures for colorectal cancer may include the following:
- Digital rectal examination (DRE) – a physician or health care provider inserts a gloved and lubricated finger into the rectum to feel for anything unusual or abnormal. This test can detect cancers of the rectum, but not the colon.
- Fecal occult blood test – checks for hidden (occult) blood in the stool. It involves placing a very small amount of stool on a special card, which is then tested in the physician’s office or sent to a laboratory.
- Sigmoidoscopy – a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum. The scope blows air into the intestine to inflate it and make viewing the inside easier.
- Colonoscopy – a procedure that allows the physician to view the entire length of the large intestine. It involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the physician to see the lining of the colon, remove tissue for further examination and possibly treat some problems that are discovered.
- Barium enema – a fluid called barium (a metallic, chemical, chalky liquid used to coat the inside of organs so that they will show up on an X-ray) is given into the rectum to partially fill up the colon. An X-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages) and other problems.
- Biopsy – a procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope to determine if cancer or other abnormal cells are present.
- Blood count – to check for anemia (a result of bleeding from a tumor).
What are the stages of colorectal cancer?
When colorectal cancer is diagnosed, tests will be performed to determine how much cancer is present and if the cancer has spread from the colon to other parts of the body. This step is called staging, and is an important step toward planning a treatment program. The National Cancer Institute defines the following stages for colorectal cancer:
|Stage 0 (Cancer in Situ)||The cancer is found in the innermost lining of the colon.|
|Stage I (also called Dukes’ A colon cancer)||The cancer has spread beyond the innermost lining of the colon to the second and third layers and the inside wall of the colon. The cancer has not spread to the outer wall of the colon or outside of the colon.|
|Stage II (also called Dukes’ B colon cancer)||The cancer has spread outside the colon to nearby tissue. However, the lymph nodes are not involved.|
|Stage III (also called Dukes’ C colon cancer)||The cancer has spread to nearby lymph nodes, but has not spread to other organs in the body.|
|Stage IV (also called Dukes’ D colon cancer)||The cancer has spread to other parts of the body, such as lungs.|