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If you want more information about how the stage of a colon cancer is determined, this is the right place. If you already know the stage of your cancer, this page will explain what your doctors are basing that determination on. There is a difference between what’s called “clinical” and “pathologic” stage that will be explained below. If you haven’t yet had definitive surgical treatment (that is, you’ve only had a biopsy), then your doctors will be making treatment recommendations based on the “clinical” stage. For colon cancer, the initial treatment is almost always a surgical removal of the cancer, unless there is already evidence of spread to other organs in the body. After the surgery, the stage is revised if needed, based on the additional information provided from the evaluation of the tissue removed.

What does “cancer stage” mean, and how is it determined?

The method of staging cancers has been well-defined for decades. There is a standard manual that has been agreed upon by virtually the entire international community of cancer experts, which is used as a reference. This manual is updated every few years. The idea is to try to categorize cancers into smaller groups that are likely to behave in similar fashion. This grouping of similar cancers allows doctors to provide more individualized treatment plans. Rather than treating all cancers the same, each stage may be treated in a way that will best fit that subgroup of cancers.

The concept of staging is essential in making the best decisions about treatment. Your surgeon should determine the stage of your cancer at the outset, based on what can be learned about your cancer from physical examination, from biopsy information, and from any imaging studies that might have been done. This is called a clinical stage. Once a definitive operation has been done, the added information from the surgery will then be used to revise the cancer stage if needed. This is called a pathologic stage.

Now, how does the staging system work? For nearly all different cancer types, the stage depends on just three things, summarized by the initials TNM. These stand for: (1) T is for tumor size, (2) N is for lymph node status, and (3) M stands for evidence of metastatic disease, or in other words, cancer spread beyond the lymph nodes. Not surprisingly, this is called the TNM staging system. The group which publishes the guidelines is call the American Joint Committee on Cancer. Most of you will not need any more detailed information on this but the link is there if you are interested in learning more.

For colon cancer, the T part of the stage is determined as shown:

Tumor Size (invasive component) T
Non-invasive (cancer “seeds”) 0 (or “Tis”, for in situ)
Extends into the submucosa 1
Extends into the muscularis (muscle layer) 2
Extends through the muscularis (muscle layer) 3
Extends through the serosa 4a
Extends into adjacent organs 4b

The N part of the stage is determined as shown:<

Lymph node status (in the “mesentery” of the colon) N
No lymph nodes with cancer 0
1 lymph node with cancer 1a
2-3 lymph nodes with cancer 1b
Small pockets of cancer cells near lymph nodes 1c
4 –6 lymph nodes with cancer 2a
7 or more nodes and some other advanced findings 2b

The M part of the stage is determined as shown:

Is metastatic disease present? M
No 0
Yes, to one “distant” organ or set of lymph nodes 1a
Yes, to more than one place 1b

Once each of these factors is determined, the three numbers are combined into a Stage. I will keep it simple at this point and just say that the higher the numbers, the higher the stage. If you want the entire summary of assessing the stage, here is a link to the American Cancer Society’s website that gives these details.

If you would like to read more about treatment specific for a given stage of colon cancer, follow the links below. Or you can go back to the colon cancer home page to decide what other information to review.

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