The following tests are often used to make a diagnosis of colon cancer:
A stool blood test is usually the first step in diagnosing colon cancer. In this test, a physician gently places a gloved finger in the rectum to check for bleeding. A negative test does not mean that you do not have colon cancer. If there is suspicion of a colon cancer, then other tests must be done.
Barium enema is a common radiological test used to identify a colon cancer. The test is typically conducted as an outpatient procedure. On the day before the test, the patient is encouraged to adhere to a liquid diet and take some laxatives or use an enema. On the day of the test, barium is gently inserted via the rectum into the colon.
Sometimes the barium is combined with air. After the entire surface of the colon is covered with barium, x-ray images are captured at different time periods. The test can identify large polyps or masses in the colon and rectum. Very small polyps can be missed on a barium enema.
Colonoscopy involves the use of flexible scope which contains a camera. The day before the colonoscopy, you will be asked to abstain from solid foods and drink only clear fluids. At the end of the day, you will be asked to take an enema and a laxative to clean the bowel. This long flexible scope is inserted via the rectum and allows the physician to examine the entire colon. The procedure is done under intravenous sedation and is relatively painless.
Virtual colonoscopy is now available in many medical centers in the nation. Instead of using a scope to look at the colon, a CT scan takes serial images of the colon. Like colonoscopy, one needs to take a bowel preparation the day before the procedure. The procedure is painless and takes less than 20 minutes to perform.
Colon Cancer Stages
Once a colon cancer has been identified, a biopsy is always done to confirm the type of cancer. Like all cancers, colon cancer is also staged. Staging determines the size of tumor and the extent of spread. The traditional tests to stage colon cancer include CT scan and/or bone scans.
The stages of colon cancer include:
- Stage 0: This is the earliest stage and also known as carcinoma in situ. The cancer growth is limited to the inner layer of the colon.
- Stage I: In this stage, the cancer has grown into the mucosa but has not spread to the outside walls of the colon.
- Stage II: The cancer has gone through the outer wall of the colon, but has not spread to adjacent lymph nodes in this stage.
- Stage III: This stage indicates a colon cancer that has spread to adjacent lymph nodes.
- Stage IV: The cancer has spread to other organs like the liver or lung in this stage.