Once colon cancer has been found, more tests will be done to determine the level of malignancy (the grade of the cancer) and to find out if the cancer has spread (or metastasized) from the prostate to other parts of the body (the staging of the cancer). The following grades and stages are used for colon cancer.

1. Determining Whether the Cancer has Metastasized (Staging)

   There are several tests that can help determine whether the cancer has spread beyond the prostate to other parts of the body, including:

   CT Scan (also called CAT Scan)

   A CT scan (or CAT scan), which stands for computerized axial tomography, uses computerized X-ray pictures to evaluate internal organs of the body. The CT scan is most often used prior to surgery (discussed further under cancer treatment) in order to identify whether the cancer has already spread to distant organs, usually the liver.

   Bone Scan

   A bone scan may show areas of rapid bone growth that can be associated with cancer. Colon cancer, when it spreads to the skeleton, typically has a classic pattern of random and variable hot spots that show up on the scan. These patterns frequently occur along the pelvis or the clavicle. The lack of these patterns does not, however, rule out the spread of the cancer. If the patterns are not visible on the scan, it may only mean that there are no cancer spots in the skeleton large enough to be detected by the equipment.

2. Grading of the Colon Cancer

   The malignancy (or aggressiveness) of the colon cancer is documented by assigning a grade to the cancer based upon the appearance of the cancer cells and how they are arranged together. These scores are broken down into three main levels:
   

   • low-grade cancer: this is the least-aggressive type of cancer. Cells from low-grade colon cancer have an appearance most like normal cells, and tend to be slow-growing. Such cancer cells are called well-differentiated.
   • intermediate-grade cancer: by the time the cancer has become intermediate-grade, it has turned more aggressive than a low-grade cancer. Intermediate-grade cancer cells have an appearance that is less like normal cells and is often faster growing than low-grade cancer cells. Such cells are called moderately-differentiated.
   • high-grade cancer: this is the most aggressive type of cancer. Cells from high-grade colon cancer are the least like normal prostate cells. They are rapid-growing and highly aggressive, often spreading into the lymph nodes and bone. Such cells are called poorly-differentiated.

   The higher the grade of the cancer, the more difficult it is to successfully treat the cancer.

3. Staging of the Colon Cancer

   The following stages are used for prostate cancer.

   Stage T1NOMO (Stage I, Dukes A)

   The tumor is limited to the mucosa and submucosa.

   Stage T2NOMO (Stage II, Dukes B1)

   The tumor extends into the muscularis

   Stage T3NOMO (Stage II, Dukes B2)

   The tumor extends into or through the serosa.

   Stage TXN1MO (Stage III, Dukes C)

   The cancer involves 1-3 regional lymph nodes but is not detectable in any other organs or in the bones.

   Stage TXN2MO (Stage III, Dukes C)

   The cancer involves 4 or more regional lymph nodes but is not detectable in any other organs or in the bones.

   Stage TXNXM1 (Stage IV, Dukes D)

   The cancer has metastasized to distant organs, such as the liver, the lung, or to the bones.

Once the diagnosis and workup are completed, a proper treatment plan can be developed.