Stomach cancer or gastric cancer, is a malignant tumor arising from the lining of the stomach. Stomach cancer cells spread by breaking away from other cancer cells and go into the bloodstream or lymphatics while others penetrate into organs near the stomach. The most common cause is infection by the bacteria Helicobacter pylori, which accounts for more than 60% of cases.
The exact cause of stomach cancer is unknown, but a number of factors can increase the risk of the disease, including:
- Gender – men have more than double the risk of getting stomach cancer than women.
- Race – being African-American or Asian may increase your risk.
- Genetics – genetic abnormalities and some inherited cancer syndromes may increase your risk
- Geography – stomach cancer is more common in Japan, the former Soviet Union, and parts of Central America and South America.
- Blood type – individuals with blood group A may be at increased risk.
- Advanced age — stomach cancer occurs more often around ages 70 and 74 in men and women, respectively.
- Family history of gastric cancer can double or triple the risk of stomach cancer.
- Lifestyle factors such as smoking, drinking alcohol, and eating a diet low in fruits and vegetables or high in salted, smoked, or nitrate-preserved foods may increase your risk
- Helicobacter pylori (H. pylori) infection of the stomach. H. pylori is a bacterium that infects the lining of the stomach and causes chronic inflammation and ulcers.
- Certain health conditions including chronic gastritis, pernicious anemia, gastric polyps, intestinal metaplasia, and prior stomach surgery.
- Work-related exposure due to coal mining, nickel refining, and rubber and timber processing and asbestos exposure.
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
Tests and Diagnosis
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. Your doctor can look for signs of cancer. 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) scan and a special type of X-ray exam sometimes called a barium swallow.
Determining the 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 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.
Staging of Stomach Cancer
Stage 0: The tumor is found only in the inner layer of the stomach. Stage 0 is also called carcinoma in situ.
Stage I is one of the following:
The tumor has invaded only the submucosa. Cancer cells may be found in up to 6 lymph nodes.
Or, the tumor has invaded the muscle layer or subserosa. Cancer cells have not spread to lymph nodes or other organs.
Stage II is one of the following:
The tumor has invaded only the submucosa. Cancer cells have spread to 7 to 15 lymph nodes.
Or, the tumor has invaded the muscle layer or subserosa. Cancer cells have spread to 1 to 6 lymph nodes.
Or, the tumor has penetrated the outer layer of the stomach. Cancer cells have not spread to lymph nodes or other organs.
Stage III is one of the following:
The tumor has invaded the muscle layer or subserosa. Cancer cells have spread to 7 to 15 lymph nodes.
Or, the tumor has penetrated the outer layer. Cancer cells have spread to 1 to 15 lymph nodes.
Or, the tumor has invaded nearby organs, such as the liver, colon, or spleen. Cancer cells have not spread to lymph nodes or to distant organs.
Stage IV is one of the following:
Cancer cells have spread to more than 15 lymph nodes.
Or, the tumor has invaded nearby organs and at least 1 lymph node.
Or, cancer cells have spread to distant organs.
The choice of treatment depends mainly on the size and location of the tumor, the stage of disease, and your general health.
Surgery remains the only curative therapy for stomach cancer. Of the different surgical techniques, endoscopic mucosal resection or EMR is a treatment for early gastric cancer (tumor only involves the mucosa) that has been pioneered in Japan, but is also available in the United States at some centers. In this procedure, the tumor, together with the inner lining of stomach is removed from the wall of the stomach using an electrical wire loop through the endoscope. The advantage is that it is a much smaller operation than removing the stomach. Endoscopic submucosal dissection or ESD is a similar technique pioneered in Japan, used to resect a large area of mucosa in one piece. If the pathologic examination of the resected specimen shows incomplete resection or deep invasion by tumor, the patient would need a formal stomach resection.
Those with metastatic disease at the time of presentation may receive palliative surgery and while it remains controversial, due to the possibility of complications from the surgery itself and the fact that it may delay chemotherapy the data so far is mostly positive, with improved survival rates being seen in those treated with this approach.
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.
Radiation therapy, also called radiotherapy may also be used to treat stomach cancer, often as an adjuvant to chemotherapy and/or surgery.
Clinical trials are studies of new treatments and new ways of using existing treatments. Participating in a clinical trial may give you a chance to try the latest treatments. But clinical trials can’t guarantee a cure. In some cases, researchers might not be certain of a new treatment’s side effects.
Screening programs are successful in detecting disease in the early stages in parts of the world where the risk of stomach cancer is much higher than in the United States. The value of screening in the United States and other countries with lower rates of stomach cancer is not clear.
The following may help reduce your risk of stomach cancer:
- Do not smoke.
- Eat a healthy foods rich in fruits and vegetables.
- Take medicines to treat reflux disease (heartburn), if you have it.
- Take antibiotics if you are diagnosed with H. pylori infection.
Outlook varies based on how much the cancer has spread by the time of diagnosis. Tumors in the lower stomach are cured more often than those in the higher stomach. Chance of a cure also depends on how far the tumor has invaded the stomach wall and whether lymph nodes are involved.
When the tumor has spread outside the stomach, a cure is not possible. In this case, the goal of treatment is to improve symptoms.