Stomach cancer, also known as gastric cancer, affects the stomach, which is found in the upper part of the abdomen and just below the ribs. The stomach is part of the body's digestive system. It produces acids and enzymes that break down food before passing it to the small intestine. The cancer can develop in any part of the stomach and spread up towards the esophagus (the tube that connects mouth to the stomach) or down into the small intestine.
Rates of stomach cancer vary widely throughout the world. In Japan, it's the most common cancer, where it affects 1 in every 1,000 people. The incidence is also very high in Chile and Iceland. In Canada, while the rates of stomach cancer aren't as high, it is still one of the top 20 most common cancers.
This type of cancer more often strikes older people, men more often than women, and people of African descent more often than Caucasians.
As with most cancers, researchers don't know yet what causes stomach cancer. Several risk factors have been identified, however. These include:
- alcohol use
- cigarette smoking
- diets high in foods that are preserved by drying, smoking, salting, or pickling
- diet low in vegetables and fruits
- exposure to chemicals used in rubber and lead manufacturing
- family history of stomach cancer
- gastric atrophy
- history of Helicobacter pylori infection
- being older than 50 years of age
- pernicious anemia
- previous stomach surgery
- people of African descent
- socioeconomic status - it's not known why, but people in lower socioeconomic classes seem to have a higher rate of stomach cancer
Symptoms and Complications
Many symptoms of stomach cancer are easily ignored as simple discomfort, which is why stomach cancer often progresses quite far before being detected. Some of these symptoms include:
- abdominal pain
- bloating after meals
- diarrhea or constipation
- heartburn or indigestion
- loss of appetite
- nausea and vomiting
- weakness or fatigue
- weight loss
- vomiting blood or passing blood through stool
Advanced stomach cancer will severely affect digestion and nutrition and may spread throughout the body, eventually causing death.
The main complication arising from treated stomach cancer is related to the surgery, where the removal of the stomach results in nutritional problems. Also, there's the possibility that the cancer can return, so it's very important to continue with follow-ups as recommended by your health care team.
Making the Diagnosis
If a doctor suspects stomach cancer, a thorough patient history will first be done. This includes asking about your lifestyle, such as tobacco or alcohol use and whether you have a family history of stomach cancer. A physical exam may follow, along with some of the following tests:
- blood tests
- stool tests called fecal occult blood test - to find blood in the stool that might not be visible to the naked eye
- barium swallow or upper gastrointestinal (GI) series - the patient swallows a barium solution and the doctor uses an X-ray to track the barium's progress as it passes through the esophagus and stomach
- endoscopy - a small tube with a light on one end is slid down the throat and into the stomach so the doctor can look directly at the stomach lining
- biopsy - using a gastroscopy instrument that's fitted with a special cutter, a small piece of tissue can be taken and examined under a microscope
If cancer is diagnosed, the doctor needs to determine the stage the cancer has reached. This may involve more tests, such as:
- chest X-rays
- computed tomography (CT) scans
- magnetic resonance imaging (MRI) scans
- PET scan
- diagnostic laparoscopy
- blood tests
In its early stages, stomach cancer is very treatable. Unfortunately, early stomach cancer causes few symptoms. Usually, a diagnosis is made when the cancer is more advanced. Because it can take some time to identify stomach cancer, only about 10% of people are diagnosed while it's still in the early stages.
The stages are defined as:
- stage 0: the cancer has not spread beyond the surface layer of stomach tissue
- stage 1: the cancer has spread just underneath the first layer of stomach tissue but hasn't yet invaded the muscles
- stage 2: the cancer has spread to the lymph nodes near the stomach or the main muscle layer
- stage 3: the cancer has spread through the muscle and to the lymph nodes but not to any organs, or it may be in nearby tissue but not in any lymph nodes
- stage 4: the cancer has spread completely through the stomach wall, lymph nodes, and organs
- recurrent: cancer has returned after treatment
Other staging systems may be used. Ask your doctor the stage of your cancer and what it means to you.
Treatment and Prevention
Stomach cancer is usually only detected once it has progressed or spread, making treatment more difficult. As with most cancers, the treatment options are radiotherapy, chemotherapy, surgery, or a combination of the three.
Treatment for stages 0 and 1 usually involves only surgery, often a partial gastrectomy (where part of the stomach is removed). If needed, the abdominal lymph nodes may also be removed. For stages 2 and 3, a gastrectomy is done along with removal of abdominal lymph nodes. To reduce the very high recurrence rate, doctors often recommend additional chemotherapy and radiotherapy after surgery.
For stage 4, treatment is aimed at easing the symptoms. This can involve surgery, chemotherapy, or radiation therapy.
Surgery is the most common treatment for gastric cancer, and usually a gastrectomy is performed. If the cancer was caught early enough, the surgeon may be able to remove only a part of the stomach, called a partial or subtotal gastrectomy. If the entire stomach is removed, this is called a total gastrectomy.
Following a gastrectomy, nutrition becomes an issue. For those who have had a partial gastrectomy, a fairly normal diet might be resumed after healing, but for patients who have had a total gastrectomy, certain changes need to be made because the food will now go straight from the esophagus to the small intestine. One example is vitamin supplementation. A monthly injection of vitamin B12 may be needed since it can't be absorbed from the diet.
To help with digestion and comfort, dieticians can suggest an appropriate diet, most likely high in protein and low in sugar. They'll also recommend frequent small meals rather than three square meals a day.
Some people with total gastrectomies experience dumping syndrome, which includes nausea, vomiting, cramping, diarrhea, and dizziness. This is caused by the food entering the intestine too quickly, without benefit of the stomach acids breaking it down. Eating smaller meals more frequently can help reduce this discomfort.
Chemotherapy involves taking medication to fight the cancer. In stomach cancer, the chemotherapy is generalized or systemic, and is usually taken intravenously, but can be administered orally in some cases.
Because chemotherapy circulates throughout the body, more of the body systems are affected by the treatment. Side effects from chemotherapy include:
- hair loss
- increased risk of infections
- mouth sores
- nausea and vomiting
Radiation therapy is an external treatment to kill the cancer cells. The radiation is aimed directly at the tumours in an effort to shrink them. Radiotherapy may be done before surgery in some cases to shrink the tumour.
Several side effects are typical of radiotherapy. They include:
- decreased appetite
- nausea and vomiting
- red, dry skin at the radiation site
It seems that some cases of stomach cancer might be prevented. Some people from Japan, which has the highest rate of stomach cancer in the world, decrease their chances of developing the cancer when they move to an area with a lower rate. This suggests that environmental factors are involved.
The risk factors listed above, including diet, can provide a clue to how we might reduce our chances of developing cancer:
- Stop smoking.
- Eat a healthy, balanced diet including regular servings of fresh fruit and vegetables.
- Don't abuse alcohol.
- Be aware of the risk factors and be sure to talk to your doctor about any concerns or symptoms.