Colorectal Cancer: Stages

What does the stage of a cancer mean?

The stage of a cancer is how much and how far the cancer has spread in your body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is. He or she can also see if the cancer has spread to nearby areas, and if it has spread to other parts of your body. The stage of a cancer is one of the most important things to know when deciding how to treat the cancer.

Colorectal cancer starts in the inner lining of the colon or rectum. As colorectal cancer grows, it can grow through the layers of the wall of the colon or rectum. Then, like all cancers, it can spread (metastasize) to other parts of the body. 

The TNM system for colorectal cancer

The most commonly used system to stage colorectal cancer is the TNM system from the American Joint Committee on Cancer. Be sure to ask your healthcare provider to explain the stage of your cancer to you in a way you can understand.

The first step is to decide the value for each part of the TNM system. Here's what the letters stand for in the TNM system::

• T tells how far the main tumor has spread into the lining of your colon or rectum and nearby tissue.

• N tells if the lymph nodes in the area of the original tumor have cancer in them.

• M tells if the cancer has spread (metastasized) to distant organs in the body, such as the liver, lung, or lining of your belly or abdomen.

Number values are assigned to the T, N, and M categories. There are also 2 other values that can be assigned:

• X means the provider does not have enough information to assess the extent of the main tumor, or if the lymph nodes have cancer cells. This value is often used before surgery.

• In situ (is) means the cancer is small and has not spread past the area where it started in the first layer of the colon or rectum wall.

What are the stage groupings of colorectal cancer? 

Stage groupings are determined by combining the T, N, and M values from the TNM system. These groupings give an overall description of your cancer. A stage grouping can have a value of 0 or of Roman numerals I through IV (1 through 4). The higher the number, the more advanced your cancer is.

These are the stage groupings of colorectal cancer and what they mean:

Stage 0. Cancer is only in the innermost lining of your colon or rectum. It has not spread into the deeper layers or anywhere else in your body. This stage is also called carcinoma in situ.

Stage I. The cancer has spread to the middle layers of the wall of your colon or rectum. It has not spread to the lymph nodes or distant sites

Stage II. This stage is divided into 3 groups:

• Stage IIA. The cancer has grown into the outermost layers of the colon or rectum but has not gone through them. It has not spread to nearby tissues, the lymph nodes, or to distant sites..

• Stage IIB. The cancer has grown through the wall of the colon or rectum but has not grown into nearby tissues or organs. It has not spread to nearby lymph nodes or distant sites.

• Stage IIC. The cancer has grown outside your colon to nearby tissues or organs. It has not spread to lymph nodes or to distant sites.

Stage III. This stage is divided into 3 groups:

• Stage IIIA. One of the following applies:

  • The cancer has spread to the first or middle layers of your colon or rectum wall. It has also spread to one to three lymph nodes or the fat near them. It hasn't spread to distant sites.

  • The cancer has grown into the first layer of the colon or rectum wall. It has also spread to four to six nearby lymph nodes. It hasn't spread to distant sites. 

• Stage IIIB. One of the following applies:

  • The cancer has grown into the outer layers of the colon or rectum or into the lining of the abdomen (belly), called the peritoneum. But it hasn't spread to nearby organs. It has spread to one to three  nearby lymph nodes or the fat near them. It has not spread to distant sites.

  • The cancer has grown into the middle or outer layers of the colon or rectum. It has spread to four to six nearby lymph nodes. It hasn't spread to distant sites.

  • The cancer has grown into the first or middle layers of the colon or rectum. It has spread to seven or more nearby lymph nodes. It hasn't spread to distant sites.

• Stage IIIC. One of the following applies:

  • The cancer has grown through the outer layers of the colon or rectum or into the lining of the abdomen (belly), called the peritoneum, but hasn't reached nearby organs. It has spread to four to six nearby lymph nodes. But it hasn’t spread to distant sites.

  • The cancer has grown into or through the outer layers of the colon or rectum or into the lining of the abdomen (belly),  called the peritoneum, but hasn't reached nearby organs. It has spread to seven or more nearby lymph nodes. But it hasn’t spread to distant sites.

  • The cancer has grown through the outer layers of the colon or rectum and has reached nearby tissues or organs. It has spread to one or more nearby lymph nodes or into areas of fat near the lymph nodes. But it hasn’t spread to distant sites.

 

Stage IV. This stage is divided into 2 sub-stages:

• Stage IVA. The cancer may or may not have grown through the wall of the colon or rectum. It may or may not have reached nearby lymph nodes. It has spread to one distant organ, such as the lungs or liver. Or it has spread to one distant set of lymph nodes, but not to the lining of the abdomen (belly), called the peritoneum.

• Stage IVB. The cancer may or may not have grown through the wall of the colon or rectum. It may or may not have reached nearby lymph nodes. It has spread to more than one distant organ, such as the liver or the lungs, or it has spread to a set of distant lymph nodes. It has not spread to distant parts of the lining of the abdomen.

• Stage IVC. The cancer may or may not have grown through the wall of the colon or rectum. It may or may not have reached nearby lymph nodes. It has spread to distant parts of the lining of the abdomen and may have spread to distant organs or lymph nodes.

Talking with your healthcare provider

Once your cancer is staged, talk with your healthcare provider about what the stage means for you. Make sure to ask questions and talk about your concerns.