Doctors need to know the stage of stomach cancer you have in order to decide what treatment to recommend. The stage is based on the size and extent of the tumor, the number of lymph nodes involved, and how far the cancer has spread. Your doctor gets this information from your biopsies, imaging tests, examination of the contents removed during surgery, and any other exams done. Staging studies for stomach cancer may include a CT scan, an endoscopic ultrasound, and laparoscopy (with or without ultrasound).
Staging for stomach cancer may not be complete until after surgery. The surgeon takes out nearby lymph nodes and may take samples of tissue from other areas in your abdomen. To check for cancer cells, a pathologist examines all contents removed during surgery. Pathologists are specially trained doctors who interpret the changes caused by disease in tissues. Decisions about treatment after surgery depend on these findings.
The most common way doctors describe the stage of stomach cancer is with the TNM system.
When you receive a diagnosis of stomach cancer, the doctor needs to know what stage the cancer is in. The American Joint Committee on Cancer has developed a standard system of describing the extent of a cancer's growth, which is the stage. This system is known as the TNM System. The TNM system is the most common one used to stage stomach cancer.
Here is what the letters stand for in the TNM system:
T refers to the size of the tumor in the stomach.
N refers to whether the lymph nodes in the area of the stomach have become cancerous.
M refers to whether the cancer has spread--metastasized--to other, distant organs in the body, such as your liver or lungs.
Once the doctor determines your T, N, and M stages, stage grouping is created. Stage grouping is used to determine your overall disease stage. It is expressed most often in Roman numerals from 0 (the least advanced) to IV (the most advanced stage). According to the National Cancer Institute, the following stage groupings are used for staging stomach cancer:
Stage 0. Also known as carcinoma in situ, the cancer is found only in the innermost layer of the stomach wall, called the mucosa, and has not spread anywhere else.
Stage I. The cancer has grown in one of these ways:
It is in the first and second layer of the stomach wall (mucosa and submucosa) and has spread to up to one or two lymph nodes very close to the tumor.
The cancer is in the first and second layer of the stomach wall, and has also invaded the muscle layer. It has not spread to lymph nodes or other organs.
Stage II. The cancer has grown in one of these ways:
It is only in the second layer of the stomach (submucosa) and has spread to seven to three or more lymph nodes very close to the tumor.
It is in the third and maybe the fourth layer of the stomach wall (muscularis and subserosa) and has spread to one to six nearby lymph nodes.
The cancer has gone through the outermost layer of the stomach wall. It has not spread to lymph nodes or other organs.
Stage III. The cancer has grown in one of these ways:
It is in the outermost layer of the stomach will (serosa) and has spread to one or two lymph nodes near the tumor
It is in the third layer of the stomach wall (the muscle layer) or subserosa and has spread to three or more lymph nodes.
It has penetrated through all five layers of the stomach wall (including the outer layers called the subserosa and the serosa). The cancer has spread to one to 15 lymph nodes very close to the tumor.
Stage IV. The cancer has spread to distant parts of the body.
Recurrent disease. Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may come back in the stomach or in another part of the body, such as the liver or lymph nodes.