Stomach Cancer

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Early Detection, Diagnosis, and Staging TOPICS

How is stomach cancer staged?

The stage of a cancer is a description of how far the cancer has spread. The stomach cancer’s stage is an important factor in choosing treatment options and predicting a patient’s outlook (prognosis).

There are actually 2 types of stages for stomach cancer.

The clinical stage of the cancer is the doctor’s best estimate of the extent of the cancer, based on the results of physical exams, endoscopy, biopsies, and any imaging tests (such as CT scans) that have been done. These exams and tests are described in the section “How is stomach cancer diagnosed?

If surgery is done, the pathologic stage can be determined using the same test results used for the clinical stage, plus what is found from tissues removed during surgery.

The clinical stage is used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates. Because the pathologic stage is based on what was found at surgery, it can more accurately predict the patient’s outlook. The staging described here is the pathologic stage.

A staging system is a way for members of the cancer care team to describe the extent of a cancer’s spread. The system most often used to stage stomach cancer in the United States is the American Joint Commission on Cancer (AJCC) TNM system. The TNM system for staging contains 3 key pieces of information:

  • T describes the extent of the primary tumor (how far it has grown into the wall of the stomach and into nearby organs).
  • N describes the spread to nearby (regional) lymph nodes.
  • M indicates whether the cancer has metastasized (spread) to distant parts of the body. The most common sites of distant spread of stomach cancer are the liver, the peritoneum (the lining of the space around the digestive organs), and distant lymph nodes. Less common sites of spread include the lungs and brain.

Numbers or letters appear after T, N, and M to provide more details about each of these factors:

  • The numbers 0 through 4 indicate increasing severity.
  • The letter X means “cannot be assessed” because the information is not available.
  • The letters “is” refer to carcinoma in situ, which means the tumor is only in the top layer of mucosa cells and has not yet invaded deeper layers of tissue.

This system is for staging all stomach cancers except those starting in either the gastroesophageal junction (where the stomach and the esophagus meet) or in the cardia (the first part of the stomach) and growing into the gastroesophageal junction. Those cancers are staged (and often treated) like cancers of the esophagus (see our document, Esophagus Cancer).

T categories of stomach cancer

Nearly all stomach cancers start in the innermost layer of the stomach wall (the mucosa). The T category describes how far through the stomach’s 5 layers the cancer has invaded.

  • The innermost layer is the mucosa. The mucosa has 3 parts: epithelial cells, which lie on top of a layer of connective tissue (the lamina propria), which is on top of a thin layer of muscle (the muscularis mucosa).
  • Under the mucosa is a supporting layer called the submucosa.
  • Below this is the muscularis propria, a thick layer of muscle that moves and mixes the stomach contents.
  • The next 2 layers, the subserosa and the outermost serosa, act as wrapping layers for the stomach.

TX: The main (primary) tumor cannot be assessed.

T0: No signs of a main tumor can be found.

Tis: Cancer cells are only in the top layer of cells of the mucosa (innermost layer of the stomach) and have not grown into deeper layers of tissue such as the lamina propria or muscularis mucosa. This stage is also known as carcinoma in situ.

T1: The tumor has grown from the top layer of cells of the mucosa into the next layers below such as the lamina propria, the muscularis mucosa, or submucosa.

  • T1a: The tumor is growing into the lamina propria or muscularis mucosa.
  • T1b: The tumor has grown through the lamina propria and muscularis mucosa and into the submucosa.

T2: The tumor is growing into the muscularis propria layer.

T3: The tumor is growing into the subserosa layer.

T4: The tumor has grown into the serosa and may be growing into a nearby organ (spleen, intestines, pancreas, kidney, etc.) or other structures such as major blood vessels.

  • T4a: The tumor has grown through the stomach wall into the serosa, but the cancer hasn’t grown into any of the nearby organs or structures.
  • T4b: The tumor has grown through the stomach wall and into nearby organs or structures.

N categories of stomach cancer

NX: Nearby (regional) lymph nodes cannot be assessed.

N0: No spread to nearby lymph nodes.

N1: The cancer has spread to 1 to 2 nearby lymph nodes.

N2: The cancer has spread to 3 to 6 nearby lymph nodes.

N3: The cancer has spread 7 or more nearby lymph nodes.

  • N3a: The cancer has spread to 7 to 15 nearby lymph nodes.
  • N3b: The cancer has spread to 16 or more nearby lymph nodes.

M categories of stomach cancer

M0: No distant metastasis (the cancer has not spread to distant organs or sites, such as the liver, lungs, or brain).

M1: Distant metastasis (the cancer has spread to organs or lymph nodes far away from the stomach).

TNM stage grouping

Once the T, N, and M categories have been determined, this information is combined and expressed as a stage, using the number 0 (zero) and the Roman numerals I through IV. This is known as stage grouping. Some stages are split into substages, indicated by letters.

Stage 0: Tis, N0, M0

This is stomach cancer in its earliest stage. It has not grown beyond the inner layer of cells that line the stomach (Tis). The cancer has not spread to any lymph nodes (N0) or anywhere else (M0). This stage is also known as carcinoma in situ.

Stage IA: T1, N0, M0

The cancer has grown beneath the top layer of cells in the mucosa into tissue below, such as the connective tissue (lamina propria), the thin muscle layer (muscularis mucosa), or the submucosa (T1). The cancer has not spread to any lymph nodes (N0) or anywhere else (M0).

Stage IB: Any of the following:

T1, N1, M0: The cancer has grown into the layer of connective tissue (lamina propria), and may have grown into the thin layer of muscle beneath it (muscularis mucosa) or deeper into the submucosa (T1). Cancer has also spread to 1 or 2 lymph nodes near the stomach (N1), but not to any distant tissues or organs (M0).

OR

T2, N0, M0: The cancer has grown into the main muscle layer of the stomach wall, called the muscularis propria (T2). It has not spread to nearby lymph nodes (N0) or to any distant tissues or organs (M0).

Stage IIA: Any of the following:

T1, N2, M0: The cancer has grown beneath the top layer of cells of the mucosa into the layer of connective tissue (lamina propria), thin muscle layer (muscularis mucosa), or the submucosa (T1). It has spread to 3 to 6 nearby lymph nodes (N2). It has not spread to distant sites (M0).

OR

T2, N1, M0: The cancer has grown into the main muscle layer of the stomach called the muscularis propria (T2). It has spread to 1 or 2 nearby lymph nodes (N1), but has not spread to distant sites (M0).

OR

T3, N0, M0: The cancer has grown through the main muscle layer into the subserosa, but has not grown through all the layers to the outside the stomach (T3). It has not spread to any nearby lymph nodes (N0) or to distant tissues or organs (M0).

Stage IIB: Any of the following:

T1, N3, M0: The cancer has grown beneath the top layer of cells of the mucosa into the layer of connective tissue (lamina propria), the thin muscle layer, or the submucosa (T1). It has spread to 7 or more nearby lymph nodes (N3). It has not spread to distant tissues or organs (M0).

OR

T2, N2, M0: The cancer has grown into the main muscle layer, called the muscularis propria (T2). It has spread to 3 to 6 nearby lymph nodes (N2), but it has not spread to distant tissues or organs (M0).

OR

T3, N1, M0: The cancer has grown into the subserosa layer, but not through all the layers to the outside of the stomach (T3). It has spread to 1 or 2 nearby lymph nodes (N1), but has not spread to distant tissues or organs (M0).

OR

T4a, N0, M0: The cancer has grown completely through all the layers of stomach wall into the outer covering of the stomach (the serosa), but it has not grown into nearby organs or tissues, such as the spleen, intestines, kidneys, or pancreas (T4a). It has not spread to any nearby lymph nodes (N0) or distant sites (M0).

Stage IIIA: Any of the following:

T2, N3, M0: The cancer has grown into the main muscle layer, called the muscularis propria (T2). It has spread to 7 or more nearby lymph nodes (N3), but has not spread to distant tissues or organs (M0).

OR

T3, N2, M0: The cancer has grown into the subserosa layer, but not through all the layers to the outside of the stomach (T3). It has spread to 3 to 6 nearby lymph nodes (N2), but it has not spread to distant tissues or organs (M0).

OR

T4a, N1, M0: The cancer has grown completely through all the layers of the stomach wall into the outer covering of the stomach (the serosa), but it has not grown into nearby organs or tissues (T4a). It has spread to 1 or 2 nearby lymph nodes (N1), but it has not spread to distant sites (M0).

Stage IIIB: Any of the following:

T3, N3, M0: The cancer has grown into the subserosa layer, but not through all the layers to the outside of the stomach (T3). It has spread to 7 or more nearby lymph nodes (N2), but it has not spread to distant sites (M0).

OR

T4a, N2, M0: The cancer has grown completely through all the layers of the stomach wall into the serosa (the outer covering of the stomach), but it has not grown into nearby organs or tissues (T4a). It has spread to 3 to 6 nearby lymph nodes (N2), but it has not spread to distant sites (M0).

OR

T4b, N0 or N1, M0: The cancer has grown through the stomach wall and into nearby organs or structures such as the spleen, intestines, liver, pancreas, or major blood vessels (T4b). It may also have spread to up to 2 nearby lymph nodes (N0 or N1). It has not spread to distant sites (M0).

Stage IIIC: Any of the following:

T4a, N3, M0: The cancer has grown completely through all the layers of the stomach wall into the serosa, but it has not grown into nearby organs or tissues (T4a). It has spread to 7 or more nearby lymph nodes (N3), but it has not spread to distant sites (M0).

OR

T4b, N2 or N3, M0: The cancer has grown through the stomach wall and into nearby organs or structures such as the spleen, intestines, liver, pancreas, or major blood vessels (T4b). It has spread to 3 or more nearby lymph nodes (N2 or N3). It has not spread to distant sites (M0).

Stage IV: Any T, any N, M1

The cancer has spread to distant organs such as the liver, lungs, brain, or bones (M1).

If you have any questions about the stage of your disease, ask your doctor to explain this to you. The stage of a stomach cancer is an important factor, but it is not the only factor in considering treatment options and in predicting outlook for survival.

Resectable vs. unresectable cancer

The AJCC staging system provides a detailed summary of how far a stomach cancer has spread. But for treatment purposes, doctors are often more concerned about whether the tumor can be removed (resected) with surgery.

  • Resectable cancers are those the doctor believes can be completely removed during surgery.
  • Unresectable cancers can’t be removed completely. This might be because the tumor has grown too far into nearby organs or lymph nodes, it has grown too close to major blood vessels, it has spread to distant parts of the body, or the person is not healthy enough for surgery.

There is no distinct dividing line between resectable and unresectable in terms of the TNM stage of the cancer, but earlier stage cancers are more likely to be resectable.


Last Medical Review: 02/15/2013
Last Revised: 04/22/2014