Gastric cancer is cancer that affects the stomach. Tests are often performed to determine gastric cancer stages, or how much the cancer has spread. Stage 0 describes cancer found in the lining of one layer of the stomach, while Stage 1 is the point at which it has spread throughout the entire layer and to as many as six lymph nodes. Stage 2 gastric cancer indicates that the disease has spread either to other layers of the stomach or to nearby lymph nodes. The most severe gastric cancer stages are Stages 3 and 4, in which cancerous cells are found in at least seven lymph nodes, other layers of the stomach wall or other organs.
Stage 0 stomach cancer is the least severe, because cancerous cells are only found in the inner lining of the stomach wall's inside layer. This is also called carcinoma in situ. Stage 1 is slightly more severe and is divided into two categories. In Stage 1A, the gastric cancer has invaded the entire inside layer of the stomach wall. Stage 1B describes cancer that has spread this far and to as many as six lymph nodes or to the middle stomach layer.
Another stage of gastric cancer is Stage 2, in which there are three possibilities. The first is that the cancer has invaded the entire innermost stomach wall layer, as well as from seven to 15 nearby lymph nodes. The second possibility is that the cancer has spread to the middle stomach wall layer, in addition to as many as six lymph nodes. The third possibility of Stage 2 stomach cancer is that it has spread to the outside stomach wall layer but not to any lymph nodes.
One of the more severe gastric cancer stages is Stage 3, which has two categories. Stage 3A indicates cancerous cells have been found in the middle stomach wall layer and from seven to 15 nearby lymph nodes. Another possibility of Stage 3A is that the cancer has spread to the outside stomach wall layer and from one to six lymph nodes. Cancer that has spread to other nearby organs but not to any lymph nodes can also qualify as Stage 3A. On the other hand, Stage 3B indicates it has spread to the outside stomach wall layer and from seven to 15 lymph nodes.
The most severe of all gastric cancer stages is Stage 4. This stage indicates cancerous cells have been found in organs near the stomach and in one or more of the lymph nodes. Cancer that affects either more than 15 lymph nodes or other areas of the body also counts as Stage 4. Many people find the most advanced gastric cancer stages, such as Stages 3 and 4, do not respond to conventional treatments because the cancer has spread so far at this point.