What is stomach cancer?
In stomach cancer (also called gastric cancer), cancer cells usually begin on the inner lining of stomach walls and then penetrate deeper into the stomach walls as the cancer develops. The tumor may grow to involve nearby organs like the liver and pancreas.
Stomach cancer is one of the most common cancers worldwide. The number of stomach cancer cases has been steadily declining over the last few decades, possibly because of widespread use of refrigeration that increased access to fresh food without preservatives and bacterial contamination.
The main cause of stomach cancer is a genetic mutation (change) in the cells of the stomach, which causes the cells to grow rapidly and eventually form a tumor. Risk factors that can increase a person’s chance of getting stomach cancer include:
Tests that examine the stomach and oesophagus are used to detect and diagnose gastric cancer. The following tests and procedures may be used:
Physical exam and history – an examination of the body to check general signs of health, and 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 used 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 in the organ or tissue that produces it.
Complete blood count (CBC) – a procedure in which a sample of blood is drawn and checked for the number of red blood cells, white blood cells, and platelets. The amount of haemoglobin (the protein that carries oxygen) in the red blood cells. The portion of the sample made up of red blood cells.
Upper GI endoscopy – a procedure to look inside the oesophagus, 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 oesophagus. An endoscope (a thin, lighted tube) is passed through the mouth and down the throat into the oesophagus.
Faecal occult blood test – a test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.
Barium swallow – a series of x-rays of the oesophagus and stomach. The patient drinks a liquid that contains barium (a silver- white metallic compound). The liquid coats the oesophagus 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, computerised tomography, or computerised axial tomography.
Endoscopic ultrasound: To find out how much of the stomach wall a tumor involves and to help assess the “stage” of the cancer, a doctor will order an endoscopic ultrasound, which uses a special type of endoscope that has an ultrasound probe. The endoscope is placed in the stomach through the mouth. The ultrasound probe is able to look through the surface of the stomach lining to the stomach wall beyond and see how much of the stomach is involved by the tumor.
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.
One or more of the following tests may be done on the samples of tissue that are removed:
Immunohistochemistry: A test that uses antibodies to check for certain antigens in a sample of tissue. The antibody is usually linked to a radioactive substance or a dye that causes the tissue to light up under a microscope.
The prognosis (chance of recovery) and treatment options depend on the following:
- The stage and extent of cancer (whether it is in the stomach only or has spread to lymph nodes or other places in the body).
- The patient’s general health.
When gastric cancer is found very early, there is a better chance of recovery. Gastric cancer is often in an advanced stage when it is diagnosed. At later stages, gastric cancer can be treated but rarely can be cured.
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. Before starting treatment, patients may want to think about taking part in a clinical trial. 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.
Four types of standard treatment are used:
Surgery: Surgery is a common treatment of all stages of gastric cancer. The following types of surgery may be 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 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 oesophagus 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.
Chemotherapy: 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 spinal column, 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.
Radiation therapy: Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near cancer. The way radiation therapy is given depends on the type and stage of the cancer being treated.
Chemoradiation: Chemoradiation combines chemotherapy and radiation therapy to increase the effects of both. Chemoradiation treatment given after surgery to increase the chances of a cure is called adjuvant therapy. If it is given before surgery, it is called neo-adjuvant therapy.
Stomach cancer can be prevented with the following practices:
The outlook for stomach cancer depends on the stage of the cancer. People in the early stages of stomach cancer have a much greater rate of survival than those at a later stage:
- If stomach cancer is found in its earliest stage and can be removed with an endoscope, the five-year survival rate is higher than 90 percent.
- If the cancer is found after it has spread to areas surrounding the stomach, the five-year survival rate is 28 percent.
- If the cancer has spread to areas beyond those surrounding the stomach, the five-year survival rate is 4 percent.