Stomach cancer is cancer that occurs in the stomach — the muscular sac located in the upper middle of your abdomen, just below your ribs. It occurs due to abnormal and uncontrolled cell growth in the stomach. Your stomach receives and holds the food you eat and then helps to break down and digest it.
Another term for stomach cancer is gastric cancer. These two terms most often refer to stomach cancer that begins in the mucus-producing cells on the inside lining of the stomach (adenocarcinoma). Adenocarcinoma is the most common type of stomach cancer.
Stomach cancer is uncommon in the United States, and the number of people diagnosed with the disease each year is declining. Stomach cancer is much more common in other areas of the world.
Most people with early stomach cancer have no signs or symptoms of the condition. In advanced stages, symptoms may include indigestion; nausea and vomiting; difficulty swallowing; feeling full after eating small amounts of food; loss of appetite; vomiting blood; fatigue; and/or weight loss. Most cases of stomach cancer occur sporadically in people with little to no family history of the condition; however, approximately 10% of stomach cancers are considered "familial." Although the underlying cause of some familial cases is unknown, genetic changes (mutations) are identified in a subset of people affected by stomach cancer. Hereditary cancer syndromes associated with a predisposition to stomach cancer include hereditary diffuse gastric cancer, Lynch syndrome, Li-Fraumeni syndrome, familial adenomatous polyposis, and Peutz-Jeghers syndrome. In other families, a cluster of stomach cancers may be due to a combination of gene(s) and/or other shared factors such as environment and lifestyle. The best treatment options for stomach cancer depend on many factors including the stage of the condition and may include surgery, chemotherapy, radiation therapy, and/or targeted therapy (such as monoclonal antibody therapy).
Signs and symptoms of stomach cancer may include:
- Feeling bloated after eating
- Feeling full after eating small amounts of food
- Heartburn that is severe and persistent
- Indigestion that is severe and unrelenting
- Nausea that is persistent and unexplained
- Stomach pain
- Vomiting that is persistent
- Weight loss that is unintentional
The exact cause of the cancer is not known. Cells start multiplying uncontrollably on their own and form a tumour. Cells from the tumour may detach itself from their place of origin and spread to the lymph nodes or through the blood stream to other parts of the body. Cancer of the stomach is commoner among people who smoke or consume alcohol. It is also commoner in the orient mainly in Japan than in other regions. There may be a demographical or dietary cause of the condition. People who have a family history of cancer are also at an increased risk. Other factors like low consumption of fruits and vegetables, lack of stomach acid and increased age are known to contribute. As the use of refrigeration for preserving foods has increased around the world, the rates of stomach cancer have declined.
In general, cancer begins when an error (mutation) occurs in a cell's DNA. The mutation causes the cell to grow and divide at a rapid rate and to continue living when a normal cell would die. The accumulating cancerous cells form a tumor that can invade nearby structures. And cancer cells can break off from the tumor to spread throughout the body.
Types of stomach cancer:
The cells that form the tumor determine the type of stomach cancer. The type of cells in your stomach cancer helps determine your treatment options. Types of stomach cancer include:
- Cancer that begins in the glandular cells (adenocarcinoma). The glandular cells that line the inside of the stomach secrete a protective layer of mucus to shield the lining of the stomach from the acidic digestive juices. Adenocarcinoma accounts for the great majority of all stomach cancers.
- Cancer that begins in immune system cells (lymphoma). The walls of the stomach contain a small number of immune system cells that can develop cancer. Lymphoma in the stomach is rare.
- Cancer that begins in hormone-producing cells (carcinoid cancer). Hormone-producing cells can develop carcinoid cancer. Carcinoid cancer in the stomach is rare.
- Cancer that begins in nervous system tissues. A gastrointestinal stromal tumor (GIST) begins in specific nervous system cells found in your stomach. GIST is a rare form of stomach cancer.
Factors that increase your risk of stomach cancer include:
- A diet high in salty and smoked foods
- A diet low in fruits and vegetables
- Eating foods contaminated with aflatoxin fungus
- Family history of stomach cancer
- Infection with Helicobacter pylori
- Long-term stomach inflammation
- Pernicious anemia
- Stomach polyps
It's not clear what causes stomach cancer, so there's no way to prevent it. But you can take steps to reduce your risk of stomach cancer by making small changes to your everyday life. For instance, try to:
Eat more fruits and vegetables. Try to incorporate more fruits and vegetables into your diet each day. Choose a wide variety of colorful fruits and vegetables.
Reduce the amount of salty and smoked foods you eat. Protect your stomach by limiting these foods. Experiment with herbs and other ways of flavoring foods that don't add sodium.
Stop smoking. If you smoke, quit. If you don't smoke, don't start. Smoking increases your risk of stomach cancer, as well as many other types of cancer. Quitting smoking can be very difficult, so ask your doctor for help.
Tests and procedures used to diagnose stomach cancer include:
- A tiny camera to see inside your stomach (upper endoscopy). A thin tube containing a tiny camera is passed down your throat and into your stomach. The lining of the stomach is also thoroughly checked for any abnormality. If any suspicious areas are found, a piece of tissue can be collected for analysis (biopsy).
- Imaging tests. Imaging tests used to look for stomach cancer include computerized tomography (CT) scans and a special type of X-ray exam sometimes called a barium swallow. An X-ray of the stomach called a barium meal upper gastrointestinal test, to check for the presence of any tumours or abnormal growths.
- A stool test may be done to check for traces of blood.
Determining the extent (stage) of stomach cancer:
The stage of your stomach cancer helps your doctor decide which treatments may be best for you. Tests and procedures used to determine the stage of cancer include:
- Imaging tests. Tests may include a CT and positron emission tomography (PET).
- Exploratory surgery. Your doctor may recommend surgery to look for signs that your cancer has spread beyond your stomach within your abdomen. Exploratory surgery is usually done laparoscopically. This means the surgeon makes several small incisions in your abdomen and inserts a special camera that transmits images to a monitor in the operating room.
Other staging tests may be used, depending on your situation.
Stages of stomach cancer:
The stages of adenocarcinoma stomach cancer include:
- Stage I. At this stage, the tumor is limited to the layer of tissue that lines the inside of the stomach. Cancer cells may also have spread to a limited number of nearby lymph nodes.
- Stage II. The cancer at this stage has spread deeper, growing into the muscle layer of the stomach wall. Cancer may also have spread to more of the lymph nodes.
- Stage III. At this stage, the cancer may have grown through all the layers of the stomach and spread to nearby structures. Or it may be a smaller cancer that has spread more extensively to the lymph nodes.
- Stage IV. This stage indicates that the cancer has spread to distant areas of the body.
Cancer of the stomach is difficult to cure unless it is found in an early stage (before it has begun to spread). Unfortunately, because early stomach cancer causes few symptoms, the disease is usually advanced when the diagnosis is made. However, advanced stomach cancer can be treated and the symptoms can be relieved.
Your treatment options for stomach cancer depend on the stage of your cancer, your overall health and your preferences.
The goal of surgery is to remove all of the stomach cancer and a margin of healthy tissue, when possible. Options include:
- Removing early-stage tumors from the stomach lining. Very small cancers limited to the inside lining of the stomach may be removed using endoscopy in a procedure called endoscopic mucosal resection. The endoscope is a lighted tube with a camera that's passed down your throat into your stomach. The doctor uses special tools to remove the cancer and a margin of healthy tissue from the stomach lining.
- Removing a portion of the stomach (subtotal gastrectomy). During subtotal gastrectomy, the surgeon removes only the portion of the stomach affected by cancer.
- Removing the entire stomach (total gastrectomy). Total gastrectomy involves removing the entire stomach and some surrounding tissue. The esophagus is then connected directly to the small intestine to allow food to move through your digestive system.
- Removing lymph nodes to look for cancer. The surgeon examines and removes lymph nodes in your abdomen to look for cancer cells.
- Surgery to relieve signs and symptoms. Removing part of the stomach may relieve signs and symptoms of a growing tumor in people with advanced stomach cancer. In this case, surgery can't cure advanced stomach cancer, but it can make you more comfortable.
- Surgery carries a risk of bleeding and infection. If all or part of your stomach is removed, you may experience digestive problems.
Radiation therapy uses high-powered beams of energy, such as X-rays and protons, to kill cancer cells. The energy beams come from a machine that moves around you as you lie on a table.
Radiation therapy can be used before surgery (neoadjuvant radiation) to shrink a stomach tumor so that it's more easily removed. Radiation therapy can also be used after surgery (adjuvant radiation) to kill any cancer cells that might remain around your stomach. Radiation is often combined with chemotherapy. In cases of advanced cancer, radiation therapy may be used to relieve side effects caused by a large tumor.
Radiation therapy to your stomach can cause diarrhea, indigestion, nausea and vomiting.
Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. Chemotherapy drugs travel throughout your body, killing cancer cells that may have spread beyond the stomach.
Chemotherapy can be given before surgery (neoadjuvant chemotherapy) to help shrink a tumor so that it can be more easily removed. Chemotherapy is also used after surgery (adjuvant chemotherapy) to kill any cancer cells that might remain in the body. Chemotherapy is often combined with radiation therapy. Chemotherapy may be used alone in people with advanced stomach cancer to help relieve signs and symptoms.
Chemotherapy side effects depend on which drugs are used. The type of stomach cancer you have determines which chemotherapy drugs you'll receive.
Targeted therapy uses drugs that attack specific abnormalities within cancer cells. Targeted drugs used to treat stomach cancer include:
- Trastuzumab (Herceptin) for stomach cancer cells that produce too much HER2.
- Ramucirumab (Cyramza) for advanced stomach cancer that hasn't responded to other treatments.
- Imatinib (Gleevec) for a rare form of stomach cancer called gastrointestinal stromal tumor.
- Sunitinib (Sutent) for gastrointestinal stromal tumors.
- Regorafenib (Stivarga) for gastrointestinal stromal tumors.