Staging is a method of evaluating the progress of colon cancer in a patient. That is, it looks at the colon cancer (tumor) and the extent to which the cancer has spread to other parts of the body. Once doctors know how far along the colon cancer is, they can decide on the best course of treatment.

Today, the most common used system for the staging of colon cancer is the American Joint Committee on Cancer's (AJCC) TNM staging system. This staging system places patients into one of four stages (Stage I, Stage II, Stage III and Stage IV).

American Joint Committee on Cancer (AJCC) Staging System

Stage 0 Colon Cancer

In Stage 0, the colon cancer is found in the innermost lining of the colon only. Stage 0 colorectal cancer is also called carcinoma in situ.

Stage I Colon Cancer

In Stage I, the colon cancer has begun to spread, but is still in the inner lining of the colon or rectum. In Stage I, the colon cancer has not reached the outer wall of the colon. Another name for Stage I colorectal cancer or Duke A.

Stage II Colon Cancer

In Stage II, the colon cancer extends more deeply into and/or through the colon or rectum. The colon cancer may have invaded nearby tissue. In Stage II, it the colon cancer has not reached lymph nodes (Lymph nodes are small, bean-shaped structures found throughout the body that filter substances in a fluid call lymph to help fight infection and disease. Another name for Stage II colorectal cancer or Duke B.

Stage III Colon Cancer

In Stage III, the colon cancer has spread to lymph nodes, but has not been carried to distant parts of the body. Another name for Stage III colorectal cancer or Duke C.

Stage IV Colon Cancer

In Stage IV, the colon cancer has been carried through the lymph system to distant parts of the body. This is known as metastasis. The most likely organs to experience metastasis from colorectal cancer are the lungs and liver. Another name for Stage IV colorectal cancer or Duke D.

Recurrent Colon Cancer or Cancerous Cells

Recurrent colon cancer is the return of cancerous cells that have already been treated. The cancerous cells could return as colorectal cancer, and/or return in any other part of the body.