Once stomach cancer is diagnosed, tests are needed to determine if the cancer is only in the stomach or has spread to other parts of the body.
The procedure to determine whether the cancer is present only in the stomach or has spread to other parts of the body is called cancer staging. The information gathered during the staging process is used to determine the stage of the disease. Cancer staging is very important in the development of a treatment plan.
The staging process may require the following tests as well as procedures.
EUS (ultrasound endoscopy): An examination in which an endoscope is inserted into the body, usually through the mouth or rectum. The endoscope is a thin, tube-like instrument with a light and a visual lens. The probe at the end of the endoscope emits high-energy sound waves (ultrasound) into the body’s internal tissues or organs and creates echoes. These echoes form images of the body’s tissues called sonograms. This process is also known as ultrasound endoscopy.
CT scan (CAT scan): A series of detailed images of internal areas of the body (such as the chest, abdomen, and pelvis) taken from different angles. These images are generated by a computer attached to an x-ray machine. It may be necessary to inject a contrast agent into the blood vessels or swallow a contrast agent so that organs and tissues appear more clearly. This procedure is also known as computed tomography, or computed tomography or computed axial tomography.
PET scan (positron emission tomography): A test that looks for malignant tumor cells in the body. A small amount of radioactive glucose is injected into a blood vessel. the PET scanner rotates around the body and takes images to see where in the body this glucose is being used. PET scans and CT scans can be done at the same time, and this is called a PET-CT exam.
MRI (magnetic resonance imaging): A test that uses magnets, radio waves, and a computer to generate a series of detailed images of the inside of the body. A substance called gadolinium is injected into a vein. The gadolinium can collect around cancer cells, so the cancer cells appear brighter in the images. This test is also known as magnetic resonance imaging (NMRI).
Laparoscopy: A surgical procedure that examines the internal organs of the abdomen and looks for signs of disease. Several small incisions are made in the abdominal wall, and a laparoscope (a thin, lighted tube) is inserted through one of the incisions. Other instruments can be inserted through the same incision or other incisions to perform certain operations, such as removing organs or taking tissue samples that can then be placed under a microscope to examine for signs of cancer. A fluid can be used to flush the surface of the abdominal organs and then aspirate that fluid to collect the cells. These cells can also be looked at under a microscope to check for signs of cancer.
There are three ways that cancer cells can spread in the body.
Cancer cells can spread through the tissues, the lymphatic system, and the blood.
Tissue. Cancer cells gradually grow and spread from the site of origin to nearby areas.
Lymphatic system. Cancer cells enter the lymphatic system from the site of origin and spread through the lymphatic vessels to other parts of the body.
Blood. Cancer cells enter the bloodstream from the site of origin and spread through blood vessels to other parts of the body.
Cancer cells are able to spread from the site of origin to other parts of the body.
When cancer cells spread to other parts of the body, that is called metastatic cancer. The cancer cells spread away from the initial site (the primary tumor) and spread through the lymphatic system or blood.
Lymphatic system. Cancer cells enter the lymphatic system, spread through the lymphatic channels to other parts of the body, and form a tumor (metastasis) at that site.
Blood. Cancer cells enter the bloodstream, spread through blood vessels to other parts of the body, and form a tumor (metastasis) at that site.
Metastases are the same type of tumor as the primary tumor. For example, if stomach cancer metastasizes to the liver, then the cancer cells in the liver are actually stomach cancer cells. This disease is metastatic gastric cancer, not liver cancer.
Many cancer deaths occur because the cancer cells have metastasized from the primary tumor to other tissues and organs. This is called metastatic cancer. This animation shows how cancer cells spread from where they first formed in the body to other parts of the body.
Gastric cancer is staged as follows:
Stage 0 (carcinoma in situ)
In stage 0, abnormal cells are found in the mucosal layer of the stomach wall (the innermost layer). These abnormal cells may become cancerous and spread to nearby normal tissues. stage 0 is also known as carcinoma in situ.
Stratification of the gastric wall. The stomach wall consists of a mucosal layer (innermost layer), a submucosal layer, a muscular layer, a subplasmic layer, and a plasma layer (outermost layer). The stomach is an organ in the upper abdomen.
Stage I
Stage I is divided into stage IA and stage IB.
Stage IA: Cancer cells have formed in the mucosal layer (innermost layer) of the stomach wall and may have spread to the submucosal layer (layer of tissue adjacent to the mucosal layer).
Stage IB: Gastric cancer.
Cancer cells have formed in the mucosal layer (innermost layer) of the stomach wall and may have spread to the submucosal layer (layer of tissue adjacent to the mucosal layer). The cancer cells have spread to 1 or 2 nearby lymph nodes; or
Cancer cells have formed in the mucosal layer of the gastric wall and have spread to the muscularis.
Stage II:
Stage II gastric cancer is divided into stage IIA and stage IIB.
Stage IIA: Gastric cancer.
May have spread to the submucosal layer of the stomach wall (a layer of tissue adjacent to the mucosal layer). The cancer has spread to 3 to 6 nearby lymph nodes; or
has spread to the muscular layer of the gastric wall. The cancer has spread to 1 or 2 nearby lymph nodes; or
has spread to the subplasma layer of the gastric wall (the connective tissue layer adjacent to the muscular layer).
Stage IIB: Gastric cancer.
May have spread to the submucosal layer of the gastric wall (a layer of tissue adjacent to the mucosal layer). The cancer has spread to 7 to 15 nearby lymph nodes; or
has spread to the muscular layer of the gastric wall. The cancer has spread to 3 to 6 nearby lymph nodes; or
has spread to the subplasma layer of the gastric wall (the connective tissue layer adjacent to the muscular layer). The cancer has spread to 1 or 2 nearby lymph nodes; or
has spread to the plasma membrane layer (outermost layer) of the gastric wall.
Stage III
Stage III gastric cancer is classified as stage IIIA, stage IIIB, and stage IIIC.
Stage III: Cancer cells have spread to.
The muscular layer of the stomach wall. The cancer has spread to 7 to 15 nearby lymph nodes; or
Subplasma layer of the gastric wall (the connective tissue layer adjacent to the muscle layer). The cancer has spread to 3 to 6 nearby lymph nodes; or
Plasma membrane layer of the gastric wall (outermost layer). Cancer cells have spread to 1 to 6 nearby lymph nodes; or
Reaching adjacent organs, such as the spleen, colon, liver, diaphragm, pancreas, abdominal wall, adrenal glands, kidneys, or small intestine, or to the dorsal aspect of the abdominal cavity.
Stage IIIB: Cancer cells.
May have spread to the submucosa (the layer of tissue adjacent to the mucosal layer) or to the muscular layer of the stomach wall. The cancer cells have spread to 16 or more nearby lymph nodes; or
has spread to the subplasma layer (the connective tissue layer adjacent to the muscularis) or to the plasma layer (the outermost layer) of the gastric wall. The cancer has spread to 7 to 15 nearby lymph nodes; or
has spread from the stomach to adjacent organs, such as the spleen, colon, liver, diaphragm, pancreas, abdominal wall, adrenal glands, kidneys, or small intestine, or to the dorsal aspect of the abdominal cavity. The cancer has spread to one to six nearby lymph nodes.
Stage IIIC: The cancer has spread to.
the subplasma layer of the gastric wall (the connective tissue layer adjacent to the muscularis), or the plasma layer (the outermost layer). The cancer has spread to 16 or more nearby lymph nodes; or
From the stomach into nearby organs, such as the spleen, colon, and liver, the diaphragm, pancreas, abdominal wall, adrenal glands, kidneys, small intestine, or the dorsal aspect of the abdominal cavity. The cancer has spread to 7 or more nearby lymph nodes.
Stage IV
In stage IV, the cancer has spread to other parts of the body, such as the lungs, liver, distant lymph nodes, and tissues around the abdominal wall.