Gastric cancer is a disease in which malignant (cancer) cells form in the lining of the stomach.
The stomach is a J-shaped organ in the upper abdomen. It is part of the digestive system, which processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) in foods that are eaten and helps pass waste material out of the body. Food moves from the throat to the stomach through a hollow, muscular tube called the esophagus. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine.
The wall of the stomach is made up of 3 layers of tissue: the mucosal (innermost) layer, the muscularis (middle) layer, and the serosal (outermost) layer. Gastric cancer begins in the cells lining the mucosal layer and spreads through the outer layers as it grows.
Stromal tumors of the stomach begin in supporting connective tissue and are treated differently from gastric cancer. See the PDQ summary on Gastrointestinal Stromal Tumors Treatment for more information.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for gastric cancer include the following:
- Having any of the following medical conditions:
- Helicobacter pylori (H. pylori) infection of the stomach.
- Chronic gastritis (inflammation of the stomach).
- Pernicious anemia.
- Intestinal metaplasia (a condition in which the normal stomach lining is replaced with the cells that line the intestines).
- Familial adenomatous polyposis (FAP) or gastric polyps.
Symptoms of gastric cancer include indigestion and stomach discomfort or pain.
In the early stages of gastric cancer, the following symptoms may occur:
In more advanced stages of gastric cancer, the following signs and symptoms may occur:
Check with your doctor if you have any of these problems.
Exams and Tests
Tests that examine the stomach and esophagus are used to detect (find) and diagnose gastric cancer.
The following tests and procedures may be used:
- Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Blood chemistry studies : A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.
- Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
- Upper endoscopy : A procedure to look inside the esophagus, stomach, and duodenum (first part of the small intestine) to check for abnormal areas. An endoscope(a thin, lighted tube) is passed through the mouth and down the throat into the esophagus.
- Barium swallow : A series of x-rays of the esophagus and stomach. The patient drinks a liquid that contains barium (a silver-white metallic compound). The liquid coats the esophagus and stomach, and x-rays are taken. This procedure is also called an upper GI series.
- 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.
- Biopsy : The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. A biopsy of the stomach is usually done during the endoscopy.
The sample of tissue may be checked to measure how many HER2 genes there are and how much HER2 protein is being made. If there are more HER2 genes or higher levels of HER2 protein than normal, the cancer is called HER2 positive. HER2-positive gastric cancer may be treated with a monoclonal antibody that targets the HER2 protein.
There are different types of treatment for patients with gastric cancer.
Different types of treatments are available for patients with gastric cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Five types of standard treatment are used:
- Subtotal gastrectomy: Removal of the part of the stomach that contains cancer, nearby lymph nodes, and parts of other tissues and organs near the tumor. The spleen may be removed. The spleen is an organ in the upper abdomen that filters the blood and removes old blood cells.
- Total gastrectomy: Removal of the entire stomach, nearby lymph nodes, and parts of the esophagus, small intestine, and other tissues near the tumor. The spleen may be removed. The esophagus is connected to the small intestine so the patient can continue to eat and swallow.
If the tumor is blocking the stomach but the cancer cannot be completely removed by standard surgery, the following procedures may be used:
- Endoluminal stent placement: A procedure to insert a stent (a thin, expandable tube) in order to keep a passage (such as arteries or the esophagus) open. For tumors blocking the passage into or out of the stomach, surgery may be done to place a stent from the esophagus to the stomach or from the stomach to the small intestine to allow the patient to eat normally.
- Endoluminal laser therapy: A procedure in which an endoscope (a thin, lighted tube) with a laser attached is inserted into the body. A laser is an intense beam of light that can be used as a knife.
- Gastrojejunostomy: Surgery to remove the part of the stomach with cancer that is blocking the opening into the small intestine. The stomach is connected to the jejunum(a part of the small intestine) to allow food and medicine to pass from the stomach into the small intestine.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.
See Drugs Approved for Stomach (Gastric) Cancer for more information.
The way the radiation therapy is given depends on the type and stage of the cancer being treated. External radiation therapy is used to treat gastric cancer.
Chemoradiation therapy combines chemotherapy and radiation therapy to increase the effects of both. Chemoradiation given after surgery, to lower the risk that the cancer will come back, is called adjuvant therapy. Chemoradiation given before surgery, to shrink the tumor (neoadjuvant therapy), is being studied.
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. Monoclonal antibody therapy is a type of targeted therapy used in the treatment of gastric cancer.
Monoclonal antibody therapy uses antibodies made in the laboratory from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells. For stage IV gastric cancer and gastric cancer that has recurred, monoclonal antibodies, such as trastuzumab or ramucirumab, may be given. Trastuzumab blocks the effect of the growth factor protein HER2, which sends growth signals to gastric cancer cells. Ramucirumab blocks the effect of the protein VEGF and may prevent the growth of new blood vessels that tumors need to grow.
Follow-up tests may be needed.
Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor.
Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer. Avoiding risk factors and increasing protective factors may lower your risk but it does not mean that you will not get cancer.
Different ways to prevent cancer are being studied, including: