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Stages of Gastric Cancer
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After gastric cancer has been diagnosed, tests are done to find out if cancer cells have spread within the stomach or to other parts of the body.
The process used to find out if cancer has spread within the stomach or to other
parts of the body is called staging. The information gathered from the
staging process determines the stage of the disease. It is important to know
the stage in order to plan treatment.
The following tests and
procedures may be used in the staging process:
- β-hCG (beta-human chorionic gonadotropin), CA-125, and CEA (carcinoembryonic antigen) assays: Tests that measure the levels of β-hCG, CA-125, and CEA in the blood. These substances are released into the bloodstream from both cancer cells and normal cells. When found in higher than normal amounts, they can be a sign of gastric cancer or other conditions.
- Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
- Endoscopic ultrasound (EUS): A procedure in which an endoscope is inserted into the body, usually through the mouth or rectum. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- Laparoscopy: A surgical procedure to look at the organs inside the abdomen to check for signs of disease. Small incisions (cuts) are made in the wall of the abdomen and a laparoscope (a thin, lighted tube) is inserted into one of the incisions. Other instruments may be inserted through the same or other incisions to perform procedures such as removing organs or taking tissue samples for biopsy.
- PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
The following stages are used for gastric cancer:
Stage 0 (Carcinoma in Situ)
In stage 0, abnormal cells are found in the inside lining of the mucosal (innermost) layer of the stomach wall. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.
Stage I
In stage I, cancer has formed. Stage I is divided into stage IA and stage IB, depending on where the cancer has spread.
Stage II
In stage II gastric cancer, cancer has spread:
- completely through the mucosal (innermost) layer of the stomach wall and is found in 7 to 15 lymph nodes near the tumor; or
- to the muscularis (middle) layer of the stomach wall and is found in up to 6 lymph nodes near the tumor; or
- to the serosal (outermost) layer of the stomach wall but not to lymph nodes or other organs.
Stage III
Stage III gastric cancer is divided into stage IIIA and stage IIIB depending on where the cancer has spread.
Stage IV
In stage IV, cancer has spread to:
- organs next to the stomach and to at least one lymph node; or
- more than 15 lymph nodes; or
- other parts of the body.
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