After diagnosis, one of the most important procedures done next is staging. Staging refers to gauging extent of the cancer and how far it has spread. Colon cancer staging is very important as it can help doctors determine the kind if treatment that is required.
The colon cancer staging is done based on the TNM system of staging.
The TNM system of staging has the following factors:
Tumor (T): This factor refers to how far the cancer has grown into the wall of the colon. These layers include, the mucosa which is the inner lining, the sub-mucosa which is the fibrous tissue below the muscle, the muscularis propria which is a thick muscle layer and the serosa which is outermost covering layer
Lymph node s (N): This factor indicates if the cancer has spread to the lymph nodes.
Metastasis (M): This factor refers to whether the cancer has spread to other parts of the body.
Classification of colon cancer stages
Within each stage, the cancer is classified and given a number or letter that indicates the extent of the disease. These numbers and letters are given based on how far the cancer has spread.
Stage 0 (Tis N0 M0)
This is the earliest stage of colon cancer and it also means that the cancer has not grown beyond the mucosa or the innermost layer of the colon
At this stage, it means the cancer has grown into the mucosa and submucosa.
In this stage, the cancer is a little more advanced than stage 1 and has grown beyond the mucosa and submucosa. Stage 2 can further be classified into stage 2A, 2B or 2C.
Stage 3 is further classified into 3A, 3B and 3C, the difference between these classifications further depends on how far the cancer has spread and the affected lymph nodes.
Stage 4 colon cancer is considered to be the most advanced stage as the cancer may have spread to one distant site like the liver or lungs. This stage is also further divided into stage 4A and 4B.