There are different stage descriptions for different types of cancer. This section covers staging of adenocarcinoma, the most common type of stomach cancer. Staging is different for gastric lymphoma, sarcoma, and carcinoid tumors.
TNM Stages of Stomach Cancer
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.
- 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.
• T categories of stomach cancer
Using the TNM system, the “T” plus a letter or number (0 to 4) is used to describe the how far the tumor has grown into the stomach. Some stages are also divided into smaller groups that help describe the tumor in even more detail. 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 primary tumor cannot be evaluated.
- T0 (T plus zero): There is no evidence of a primary tumor in the stomach.
- Tis: This stage describes a condition called carcinoma (cancer) in situ. The cancer is found only in cells on the surface of the inner lining of the stomach called the epithelium and has not spread to any other layers of the stomach.
- T1: The tumor has grown into the lamina propria, muscularis mucosae, or the submucosa, which are the inner layers of the wall of the stomach.
- 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 has grown into the muscularis propria, the muscle layer of the stomach.
- T3: The tumor has grown through all of the layers of the muscle into the connective tissue outside the stomach, but it has not grown into the lining of the abdomen, called the peritoneal lining, or into the serosa, which is the outer layer of the stomach.
- T4: The tumor has grown through all of the layers of the muscle into the connective tissue outside the stomach and has grown into the peritoneal lining or serosa or the organs surrounding the stomach
- 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
The “N” in the TNM staging system is for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes inside the abdomen are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes. The overall prognosis for patients with stomach cancer is based on how many regional lymph nodes show signs of cancer. If six lymph nodes or fewer have cancer, the prognosis is better than if more than 15 lymph nodes contain cancer cells.
- 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 seven to 15 regional lymph nodes.
- N3b: The cancer has spread to 16 or more regional lymph nodes.
• M categories of stomach cancer
The “M” in the TNM system indicates whether the cancer has spread to other parts of the body.
- MX: Distant metastasis cannot be evaluated.
- M0 (M plus zero): No distant metastasis (the cancer has not spread to distant organs or sites, such as the liver, lungs, or brain).
- M1: The cancer has spread to another part or parts of the body.
Stomach Cancer 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. The Stages of Stomach Cancer.• Stage 0: This is also called carcinoma in situ. The cancer is found only on the surface of the epithelium. The cancer has not grown into any other layers of the stomach and is considered an early cancer (Tis, N0, M0).
• Stage IA: The cancer has grown into the inner layer of the wall of the stomach, but it has not spread to any lymph nodes or other organs (T1, N0, M0).
• Stage IB: Stomach cancer is called stage IB in either of these two conditions:
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
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. The Stages of Stomach Cancer.