Colon Cancer Diagnosis
There are several different types of tests for colorectal cancer. After reviewing your medical history and doing a basic medical exam, your doctor will most likely perform one of the following:
Digital Rectal Exam
Your doctor will insert a lubricated, gloved finger into your rectum to check for lumps or abnormal areas. About half of colon cancers can be detected in this way, especially if your doctor performs a fecal occult blood test at the same time.
X-ray of the Large Intestine
Usually done with the addition of a contrast medium to create a better image of the bowel surface, an x-ray can help identify the presence of polyps.
Fecal Occult Blood Test
A small stool sample is placed on a special card and tested for hidden blood. Keep in mind that there are many causes for blood in the stool, so if this test is positive, your doctor will usually follow up with a more specific test, such as an endoscopy.
Your doctor will insert a flexible tube containing a small camera into your bowel to look for irregularities, such as polyps. There are two types of endoscopy: sigmoidoscopy and colonoscopy. A sigmoidoscopy is used to search for polyps, tumors or abnormal growths inside the lower colon and rectum. A colonoscopy—the usual standard for examining the colon—can examine the entire colon and rectum for abnormalities, and, if any are discovered, they can be removed for further testing.
A new type of procedure that’s still being studied, a virtual colonoscopy uses a combination of computer software and CT imaging to examine the colon for polyps. Benefits of this procedure include that it does not require the insertion of any firm tubes, there is no risk of injury to the bowel, sedation is not needed and recovery time is shorter. However, if a polyp is found using virtual colonoscopy, a secondary procedure will need to be done to remove it for testing.
If you are diagnosed with colon cancer, staging will help determine whether the cancer has spread to other parts of your body. Tests to determine the stage of your cancer include urine and blood tests, x-rays, barium enemas, CT scans, ultrasonography, MRI scans and PET scans.
The following staging classifications are used to identify how and where colon cancer has spread:
Abnormal cells are only found in the innermost lining of the colon.
Cancer has spread to the second and third layers of the colon and involves the inside wall of the colon. However, it has not spread outside the colon wall.
Cancer has spread beyond the colon wall and as far as the fat or thin skin wall that surrounds the colon and rectum, but it has not yet gone into the lymph nodes.
Cancer has spread to the nearby lymph nodes, but not to other areas of the body.
Cancer has spread to other parts of the body, such as the liver and lungs.
Cancer is labeled as recurrent if it returns after you’ve already undergone treatment.