Stages of colorectal cancer

The type of treatment you will receive for your colorectal cancer depends on what stage it is in. Staging is a process doctors use to describe how far the cancer has spread.

Although there are several methods of staging, most doctors now use the TNM method. The TNM method is based on the size of the tumour (T), the spread of the cancer into nearby lymph nodes (N), and the spread of the cancer to other body parts (M, for metastasis). Some doctors still use an older method of staging called Dukes.

TNM staging labels
T (describes tumour size and how deeply it has penetrated the tissue layers of the colon or rectum) N (describes how far the cancer has spread to nearby lymph nodes) M (describes whether the cancer has spread to other parts of the body—metastasized)
  • Tis:The tumour is "in situ," meaning it was caught very early and has not grown beyond the lining of the colon or rectum.
  • T1: The tumour has grown through the lining and into the connective tissue.
  • T2: The cancer has grown into the thick inner muscle.
  • T3:The cancer has grown completely through the thick inner muscle. It has spread to the outer lining but not to any nearby organs or tissues.
  • T4:The cancer has spread completely through the wall of the colon or rectum and into nearby tissues or organs.
  • N0: Cancer has not spread to lymph nodes.
  • N1: Cancer cells are found in 1 to 3 regional lymph nodes.
  • N2: Cancer cells are found in 4 or more regional lymph nodes.
  • M0: Cancer cells have not spread to other parts of the body.
  • M1: Cancer cells have spread to other parts of the body.

Let’s say your doctor has told you your cancer is at stage II. In the table below, find the column labelled "TNM stage." Now go down to the row labelled "Stage II." In the "Stage II" box are some letters and numbers: “T3 or T4, N0, M0.” These are labels from the TNM staging system. This is what they mean: The tumour has grown into the outer layer of the intestine (T3) or completely through the intestine's wall into nearby tissues or organs (T4); it has not spread to nearby lymph nodes (N0) or to other parts of the body (M0).

How colorectal cancer is staged
TNM stage Description

Stage 0

(Tis, N0, M0)

The tumour was caught early and has not grown beyond the first layer of cells in the colon or rectum (Tis). It has not spread to nearby lymph nodes (N0) or to other parts of the body (M0).

Stage I

(T1 or T2, N0, M0)

The tumour has spread into the middle layers of the colon or rectum (T1 or T2). It has not spread to nearby lymph nodes (N0) or to other parts of the body (M0).

Stage II

(T3 or T4, N0, M0)

The tumour has spread into the outer wall of the colon or rectum (T3, stage IIA) or completely through the wall (T4, stage IIB). It has not spread to nearby lymph nodes (N0) or to other parts of the body (M0).

Stage III

  • Stage IIIA (T1 or T2, N1, M0): The tumour has spread into the middle layers of the colon or rectum (T1 or T2), and it has spread to 1 to 3 lymph nodes in the area (N1).
  • Stage IIIB (T3 or T4, N1, M0): The tumour has spread into the outer wall (T3) or completely through the wall (T4). It also has spread to 1 to 3 lymph nodes (N1).
  • Stage IIIC (T-any, N2, M0): The tumour (T-any) has spread to 4 or more lymph nodes (N2).

Stage IV

(T-any, N-any, M1)

Cancer has spread, or metastasized, to other parts of the body, such as the liver, lung, or ovary (M1).

The Dukes staging system lists the stages as A, B, C, and D. The Dukes stages A through D are the same as TNM stages I through IV.

Last Updated: October 1, 2008

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