Colon cancer can further be classified within each category, wherein a number or letter is assigned to indicate the extent of the disease. These classifications are normally based on the structure of the colon and also on how far the cancer has grown through the layers of the colon wall. This article presents a detailed classification of the stages of colon cancer:

1. Stage 0
Being the earliest stage of colon cancer, this stage means that the cancer has not grown beyond the mucosa or the innermost layer of the colon.

2. Stage 1
The indications of stage 1 cancer shows that the cancer has grown into the next layer of the colon known as the mucosa and has then moved on to the second layer of the colon, which is known as the submucosa. However, in this stage the cancer has not yet spread to the lymph nodes.

3. Stage 2

The cancer in stage 2 is a little more advanced than in stage 1 and has grown beyond the mucosa and submucosa of the colon. Stage 2 colon cancer can be further classified as stage 2A, 2B, or 2C based on the intensity of the disease.

4. Stage 2A
Although the cancer at this stage has reached the outer layer of the colon, it has not grown through it completely. It has also not reached the lymph nodes or nearby tissues at this stage.

5. Stage 2B
The cancer at this stage has still not reached the lymph nodes, but it has grown through the outer layer of the colon and also to the visceral peritoneum. The visceral peritoneum is the membrane that holds all the abdominal organs in place.

6. Stage 2C
In stage 2C, the cancer is still not seen in the lymph nodes. In addition to growing through the outer layer of the colon, the cancer has grown and spread to the nearby organs and structures.

7. Stage 3
Like stage 2, stage 3 colon cancer is also further classified as stage 3A, 3B, and 3C.

8. Stage 3A
Although the tumor has not spread to distant nodes or organs, it has grown through the muscular layers of the colon and is also found in the nearby lymph nodes.

9. Stage 3B
In this stage, the cancer has spread to at least one to three lymph nodes and it has also invaded the other organs or structures.

10. Stage 3C
The tumor in this stage has grown beyond the muscular layers and is found in four or more lymph nodes.

11. Stage 4
Stage 4 colon cancer is further classified into stage 4A and 4B.

12. Stage 4A
The cancer has now spread to one distant site such as the liver or the lungs.

13. Stage 4B
This stage is the most advanced stage of colon cancer wherein the cancer has spread to two or more distant sites.