Colon and rectal cancer

What stage is your cancer?

Your doctor will want to know whether your cancer has spread. This is because your treatment will be based on how far the cancer has moved around your body.

Doctors use numbers and letters to describe how far your cancer has spread. This is called "staging." The two most common systems for staging colon and rectal cancer are the Dukes' classification system and the tumor-node-metastasis (TNM) system. Your doctor will probably use the TNM system more than the Dukes' system. The TNM system is international.

Here's an overview of the two systems and how they relate to one another.

The Dukes classification system

This system has been used for more than 60 years.

Source:
Dukes CE.
The surgical pathology of rectal cancer.
Journal of Clinical Pathology. 1949; 2: 95-98.

¹ It classifies colon and rectal cancers according to:

How far the tumor has spread into the wall of your colon or rectum
Whether or not the cancer has spread to your

lymph nodes
Lymph nodes (also called glands) are small, bean-shaped lumps that you cannot usually see or easily feel. They are located in various parts of the body, such as the neck, armpit and groin. Lymph nodes filter the lymph fluid and remove unusual things, such as bacteria and cancer cells.

lymph nodes
Whether or not the cancer has spread to any other parts of your body (this is called metastasis).

Here's what the different stages mean:

Dukes stage	What it means
A	Your cancer has not spread beyond the wall of your colon or rectum.
B	Your cancer has spread into the muscle layer of your colon or rectum.
C	Your cancer has spread to one or more lymph nodes.
D	Your cancer has spread to your liver, bone or lung. (The cancer has metastasized.)

The tumor-node-metastasis (TNM) system

The TNM system is more detailed than the Dukes' system, although both methods look at similar things.

Source:
American Joint Committee on Cancer Staging.
AJCC cancer staging manual: colon and rectum.
5th edition. Lippincott-Raven, Philadelphia; 1997.

Source:
International Union Against Cancer.
Colon and rectum.
In: TNM classification of malignant tumours. 5th edition. Wiley, New York, U.S.A.; 1997.

In the TNM system:

T is for tumor
N is for (lymph) nodes
M is for metastasis.

Each letter is also given a number.

For T: the number tells you how big the tumor is.
For N: the number tells you which lymph nodes have cancer cells in them.
For M: the number tells you whether or not your cancer has spread outside your colon or rectum. Cancer usually spreads to the nearest lymph nodes and then to other parts of the body.

In general, lower numbers mean your cancer is less serious.

	TNM code	What it means
T (tumor)	T0	There is no evidence of a tumor.
	Tis	Your cancer hasn't spread beyond the first layer of cells in your colon or rectum wall. This is also called cancer in situ.
	T1	Your cancer has reached the first layer of cells in your colon or rectum wall.
	T2	Your cancer has spread into the muscle layer of your colon or rectum wall.
	T3	Your cancer has spread beyond the muscle layer of your colon or rectum wall.
	T4	Your cancer extends from your colon or rectum wall into other tissues next to it or into another part of your bowel.
N (regional lymph nodes)	N0	Your cancer has not spread to the nearest lymph nodes.
	N1	Your cancer has spread to one, two or three lymph nodes nearby.
	N2	Your cancer has spread to four or more lymph nodes nearby.
M (distant metastasis)	M0	Your cancer has not spread to another part of your body.
M (distant metastasis)	M1	Your cancer has spread to another part of your body. (This may mean it has spread to lymph nodes in another part of your body or to another organ such as your liver.)

If your colon or rectal cancer is staged as T1N0M0, this means that your cancer hasn't spread farther than the first layer of cells in your colon. It has not spread to the lymph nodes nearest to it, and it has not spread anywhere else in your body. This is also called stage 1 (see below).

Simplifying the TNM system

There is another step to working out how advanced your cancer is. A group of experts called the International Union Against Cancer has a way of simplifying the TNM system. In it, stage 0 is the least severe cancer and stage 4 is the most severe cancer.

The table below shows how the TNM codes and stages match up with the Dukes' stages.

Source:
Winawer SJ, Fletcher RH, Miller L, et al.
Colorectal cancer screening: clinical guidelines and rationale.
Gastroenterology. 1997; 112: 594-642.

⁴

TNM code	Dukes stage	TNM stage
Tis, N0, M0	---	0
T1, N0, M0	A	1
T2, N0, M0	B	1
T3, N0, M0	B	2
Any T, N1, M0	C	3
Any T, Any N, M1	D	4

Sources for the information on this page:

Dukes CE.The surgical pathology of rectal cancer.Journal of Clinical Pathology. 1949; 2: 95-98.

American Joint Committee on Cancer Staging.AJCC cancer staging manual: colon and rectum.5th edition. Lippincott-Raven, Philadelphia; 1997.

International Union Against Cancer.Colon and rectum.In: TNM classification of malignant tumours. 5th edition. Wiley, New York, U.S.A.; 1997.

Winawer SJ, Fletcher RH, Miller L, et al.Colorectal cancer screening: clinical guidelines and rationale.Gastroenterology. 1997; 112: 594-642.

This information was last updated on May 08, 2009

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