Colon and Rectal Cancer Stages

Staging is a process that tells the doctor how widespread the cancer may be — that is, whether the cancer has spread and how far. The stage of a cancer is one of the most important factors in selecting treatment options and predicting outcome. If you have any questions about your stage, please discuss them with your doctor.

A staging system is a standardized way in which the cancer care team describes the extent to which a cancer has spread. Staging systems for colorectal cancer include the older Dukes and Astler-Coller systems as well as the more modern AJCC/TNM system. This document uses the American Joint Committee on Cancer (AJCC) system, also called the TNM System. All 3 systems describe the spread of the cancer in relation to the layers of the wall of the colon or rectum, nearby lymph nodes, other organs next to the colon and rectum, and organs farther away.

In addition, there are 2 types of AJCC stages. The clinical stage is based on physical examination and some imaging studies done before surgery. The clinical stage is used to decide which, if any, operations should be done for people with colorectal cancer. After colorectal surgery, the pathologic stage is determined by examining the body tissue that has been removed. The pathologic stage is used to decide which patients with colon and rectal cancer should receive adjuvant treatment and, if so, exactly which treatment.

The TNM System describes the extent of the primary t umor (T), the absence or presence of metastasis (spread) to nearby lymph n odes (N), and the absence or presence of distant m etastasis (M).

The layers of the colon wall

T Categories for Colorectal Cancer

T stages of colorectal cancer describe how far the cancer has spread through the layers that form the wall of the colon and rectum. These layers, from the inner to the outer, include the mucosa (the lining) which includes the muscularis mucosae (a thin layer of muscle tissue beneath the mucosa), the submucosa (connective tissue beneath this thin muscle layer), the muscularis propria (a thick layer of muscle that contracts to force the contents of the intestines along), the subserosa (a thin layer of connective tissue), and the serosa (a thin layer that covers the outer surface of some parts of the large intestine).

Tis: The cancer is in the earliest stage. It has not grown beyond the mucosa (inner layer) of the colon or rectum. This stage is also known as carcinoma in situ or intramucosal carcinoma.

T1:The cancer has grown through the mucosa and extends into the submucosa.

T2: The cancer has grown through the mucosa and the submucosa and extends into the thick muscle layer.

T3: The cancer has grown through the mucosa, the submucosa, and completely through the thick muscle layer. It has spread to the subserosa but not to any nearby organs or tissues.

T4: The cancer has spread completely through the wall of the colon or rectum into nearby tissues or organs.

N Categories for Colorectal Cancer

N0: No lymph node involvement.

N1: Cancer cells found in 1 to 3 regional lymph nodes.

N2: Cancer cells found in 4 or more regional lymph nodes.

M Categories for Colorectal Cancer

M0: No distant spread.

M1: Distant spread is present.

Stage grouping

Once a patient’s T, N, and M categories are known, this information is combined to determine the stage, expressed in Roman numerals from stage I (the least advanced stage) to stage IV (the most advanced stage). The following table illustrates how TNM categories are grouped together into stages.

Stage	TNM Category
Stage 0:	Tis, N0, M0
Stage I:	T1, N0, M0 T2, N0, M0
Stage IIA: Stage IIB:	T3, N0, M0 T4, N0, M0
Stage IIIA: Stage IIIB: Stage IIIC:	T1-T2, N1, M0 T3-T4, N1, M0 Any T, N2, M0
Stage IV:	Any T, Any N, M1

Stage 0: Tis, N0, M0: The cancer is in the earliest stage. It has not grown beyond the inner layer (mucosa) of the colon or rectum. This stage is also known as carcinoma in situ or intramucosal carcinoma.

Stage I: T1, N0, M0, or T2, N0, M0: The cancer has grown through the mucosa into the submucosa (T1) or it may also have grown into the muscularis propria (T2), but it has not spread into nearby lymph nodes (N0) or distant sites.

Stage IIA: T3, N0, M0: The cancer has grown through the wall of the colon or rectum, into the outermost layers (T3). It has not yet spread to the nearby lymph nodes (N0) or distant sites.

Stage IIB: T4, N0, M0: The cancer has grown through the walls of the colon or rectum into other nearby tissues or organs (T4). It has not yet spread to the nearby lymph nodes (N0) or distant sites.

Stage IIIA: T1-2, N1, M0: The cancer has grown through the mucosa into the submucosa (T1) or it may also have grown into the muscularis propria (T2), and it has spread to 1 to 3 nearby lymph nodes (N1) but not distant sites.

Stage IIIB: T3-4, N1, M0: The cancer has grown through the wall of the colon or rectum (T3) or into other nearby tissues or organs (T4) and has spread to 1 to 3 nearby lymph nodes (N1) but not distant sites.

Stage IIIC: Any T, N2, M0: The cancer can be any T but has spread to 4 or more nearby lymph nodes but not distant sites.

Stage IV: Any T, Any N, M1: The cancer can be any T, any N, but has spread to distant sites such as the liver, lung, peritoneum (the membrane lining the abdominal cavity), or ovary (M1).

The Dukes system uses letters A through C, and the Astler-Coller system uses A through D. If your stage is reported in either of these systems, this table can be used to find the matching AJCC/TNM stage:

AJCC/TNM	Dukes	Astler-Coller
O	-	-
I	A	A, B1
II	B	B2, B3
III	C	C1, C2, C3
IV	-	D

COLON AND RECTAL CANCER WORK-UP (EVALUATION)

TYPES OF COLON AND RECTAL CANCER TREATMENTS

For more information on these treatment guidelines, or on cancer in general, call the NCCN at 1-888-909-NCCN or the American Cancer Society at 1-800-ACS-2345. Or you can visit these organizations’ web sites at www.cancer.org (ACS) and www.nccn.org (NCCN).

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