If you are diagnosed with colon cancer, your doctor will determine the stage of the disease. Staging is a way of classifying cancer by how much disease is in the body and where it has spread at the time of diagnosis. This helps us to plan the best way to treat the cancer. Once the staging classification is determined, it stays the same even if treatment works or the cancer spreads.

Stage 0: Abnormal cells are found in the inner lining of the colon. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 also is called carcinoma in situ.

Stage 1: Cancer has formed and spread into the first (submucosa) or second (muscle) layers of the rectal wall. It has not spread outside of the rectum.

Stage 2: Cancer has spread outside of the rectal walls into the surrounding fat or nearby tissue. It has not gone into the lymph nodes.  It is divided into stages 2A, 2B or 2C depending on the extent of local tumor involvement.

Stage 3: Cancer has spread to nearby lymph nodes. It has not spread to other parts of the body.  It is divided into stages IIIA, IIIB or IIIC depending on the extent of local tumor involvement and the number of lymph nodes that contain cancer.

Stage 4: Cancer has spread to other parts of the body, such as the liver, lungs or ovaries. It is divided into stages 4A and 4B depending on the number of different parts of the body to which the cancer has spread.