What does the stage of a cancer mean?
The stage of a cancer is how much and how far it has spread in your body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is.
Scans can also show 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 on treatment.
The place where cancer starts is called the primary site. Stomach cancer can spread from the primary site (in the stomach) 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)
Muscularis propria (the muscle layer)
Serosa (the lining that covers the outside of the stomach)
Stomach cancer starts in the inner lining, or mucosa, of the stomach. As it grows, it can grow through the layers of the wall of the stomach. Then 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). Staging is very complex. 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 find 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 near the primary tumor have cancer in them.
M tells if the cancer has spread ( metastasized) to distant organs in the body, like the liver, lungs, or lining of your belly or abdomen (called 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 tell the extent of the primary tumor, or if the lymph nodes have cancer cells in them.
0 means no sign, such as no sign of cancer in lymph nodes (N0).
What are the stage groupings of stomach cancer?
The T, N, and M values from the TNM system are used to put these cancers into stage groupings. These groupings give an overall description of your cancer. A stage grouping can have a value of 0 or Roman numerals I (1), II (2), III (3), or IV (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). Very abnormal looking cells (called high grade dysplasia) that will likely become cancer or cancer is found, but only in the mucosa.
Stage I. The cancer has not spread to distant organs. But it has grown in 1 of these ways:
Stage II. The cancer has not spread to distant organs. But it has grown in 1 of these ways:
Stage III. The cancer is not in distant organs and has grown in 1 of these ways:
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, liver, or brain.