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.

The place where cancer starts is called the primary site. Stomach cancer can spread from the primary site to other parts of your body. Cancer that has spread is called metastatic cancer. When a cancer spreads, it’s said to have metastasized.

To better understand staging, it helps to know the names of the layers that make up the stomach wall. From the inside to the outside, the layers are:

• Mucosa (the innermost lining)

• Submucosa

• Muscularis propria (the muscle layer)

• Subserosa

• Serosa (the lining that covers the outside of the stomach)

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

The TNM system for stomach cancer

The most commonly used system to stage stomach cancer is the TNM system from the American Joint Committee on Cancer (AJCC). 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 stomach 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, lungs, or lining of your belly or abdomen (the peritoneum).

Numbers or letters after T, N, and M provide more details about each of these factors. There are also two 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 in them.

• 0 means no sign, such as no sign of lymph node spread (N0).

What are the stage groupings of stomach 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 stomach cancer and what they mean:

Stage 0 ( also called carcinoma in situ). The cancer is found only in the mucosa.

Stage I . The cancer is not in the distant organs. But it has grown in one of these ways:

• Stage IA. The cancer spread deeper than the mucosa. But it's not in the lymph nodes.

• Stage IB. This stage can be either of these:

  • The cancer has grown deeper than just the mucosa and has spread to one or two lymph nodes close to the tumor.

  • The cancer is in the muscle layer of the stomach. But it has not spread to lymph nodes.

Stage II . The cancer is not in the distant organs. But it has grown in one of these ways:

• Stage IIA. This stage can be any of these:

  • The cancer has spread through the inside layers of the stomach, but has not grown through the outer muscle layer. It has also spread to three to six lymph nodes close to the tumor.

  • The cancer has spread into the muscle layer of the stomach and has spread to one or two nearby lymph nodes.

  • The cancer has gone through the outermost layer of the stomach, but not through the lining outside the stomach serosa. It has not spread to lymph nodes.

• Stage IIB. This stage can be any of these:

  • The cancer has grown into the inside layers of the stomach, and has spread to seven to 15 lymph nodes close to the tumor.

  • The cancer has grown into the muscle layer of the stomach. It’s also spread to three to six lymph nodes near the tumor.

  • The cancer has gone through the layers of the stomach, but not through the serosa. Cancer is also found in one or two nearby lymph nodes.

  • The cancer has grown completely through all the layers of the stomach, including the serosa. But it’s not in nearby lymph nodes, organs, or other tissues.

Stage III. The cancer is not in distant organs and has grown in one of these ways:

• Stage IIIA. This stage can be any of these:

  • The cancer has grown through the inside layers to the muscle layer of the stomach. It has also spread to seven to 15 nearby lymph nodes.

  • The cancer has grown through the layers of the stomach, but not through the serosa. It has spread to three to six nearby lymph nodes.

  • The cancer has grown through all the layers of the stomach, including the serosa. It's in one or two nearby lymph nodes, but it’s not in any other nearby organs or tissues.

  • The cancer has grown through all the layers of the stomach, including the serosa. It's in three to six nearby lymph nodes, but it’s not in any other nearby organs or tissues.

  • The cancer has gone through all the layers of the stomach, including the serosa, and into nearby organs and tissues. It has not spread to nearby lymph nodes.

• Stage IIIB. This stage can be any of these:

  • The cancer has grown through the inside layers to the muscle layer of the stomach, and has spread to 16 or more nearby lymph nodes.

  • The cancer has grown into the muscle layer of the stomach, and has spread to 16 or more nearby lymph nodes.

  • The cancer has grown into the subserosa layer of the stomach, and has spread to 7 to 15 nearby lymph nodes.

  • The cancer has gone through all the layers of the stomach, including the serosa. It's in 7 to 15 nearby lymph nodes, but it’s not in any other nearby organs or tissues.

  • The cancer has gone through all the layers of the stomach and into nearby organs and tissues. It has spread to one or two nearby lymph nodes.

  • The cancer has gone through all the layers of the stomach and into nearby organs and tissues. It has spread to three to six nearby lymph nodes.

• Stage IIIC. This stage can be any of these:

  • The cancer has grown into the subserosa layer of the stomach, and has spread to 16 or more nearby lymph nodes.

  • The cancer has gone through all the layers of the stomach, including the serosa. It's in 16 or more nearby lymph nodes, but it’s not in any other nearby organs or tissues.

  • The cancer has gone through all the layers of the stomach and into nearby organs and tissues. It has spread to seven to 15 nearby lymph nodes.

  • The cancer has gone through all the layers of the stomach and into nearby organs and tissues. It has spread to 16 or more nearby lymph nodes.

Stage IV. The cancer has grown into any layers of the stomach and may or may not have spread to lymph nodes. It has spread beyond the stomach to distant parts of the body, such as the lungs, bones, or brain.

Recurrent disease. This means that your cancer has come back (recurred) after it’s been treated. It may come back in your stomach or in another part of the body, such as your liver 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. Ask any questions and talk about your concerns.