Introduction
Stomach (gastric) cancer affects approximately 160,000 people in Europe every year.
Cancers starting in the lower part of the stomach mainly affect people over the age of 55, and are almost twice as common in men than women. Cancer in this part of the stomach is less common than it used to be - the incidence has reduced by 50% compared with 30 years ago.
But cancers arising in the upper part of the stomach near the junction with the oesophagus are becoming more common and can affect people in their 40s.
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The Stomach
The stomach is the upper part of the digestive tract, or gut. It is a muscular, bag-like organ which expands after food is eaten. It is the link between the oesophagus (gullet) and the small intestine (bowel). Once food has been swallowed, it passes down the oesophagus to the stomach where the process of digestion begins.
The wall of the stomach is lined with glands which produce acid and digestive enzymes. Most stomach cancers, the adenocarcinomas, come from these glands. The stomach lining also produces a substance which helps to absorb vitamin B12. People who do not produce this substance develop a particular form of anaemia called pernicious anaemia.
Underneath the glandular layer or mucosa, are other tissues including smooth muscle from which the gastrointestinal stromal tumours or sarcomas develop.
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Stomach Cancer
The vast majority of stomach cancers, in both the upper and lower part of the stomach, are adenocarcinomas (cancers that develop from the cells in the glands lining the stomach).
A much less common cancer is GastroIntestinal Stromal Tumour (GIST) or sarcoma of the stomach, which develops in the muscle or connective tissue of the wall of the stomach and other parts of the gut. These account for 1-3% of all gastrointestinal malignancies.
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Stomach Cancer Risk Factors
There are a number of known risk factors making you more likely to develop stomach cancer:
- Stomach cancer affects men almost twice as often as women.
- Cancer of the lower part of the stomach is rare below the age of 50 and most people who develop stomach cancer are in their 60s, 70s, and 80s.
- Cancer of the upper part of the stomach usually occurs in people in their 40s. There is an association between this type of stomach cancer and Barrett’s oesophagus (see below).
- Stomach cancer is more common in Eastern Europe, as well as in a number of areas outside Europe, notably Japan.
- Diets with large amounts of smoked foods, salted fish and meat are associated with higher rates of stomach cancer, but fresh fruits and vegetables containing antioxidant vitamins (such as A and C) lower the risk.
- Smoking increases stomach cancer risk.
- Obesity is a possible cause of many cancers, including stomach cancer.
- Infection with the bacterium Helicobacter pylori (H. pylori) is associated with cancers in the lower part of the stomach. Infection causes inflammation which can, over time, develop into cancer. But many people with H. pylori infection do not develop stomach cancer.
- Pernicious anaemia occurs in people whose stomach lining fails to produces a substance which helps to absorb vitamin B12. Vitamin B12 is necessary for the production of red blood cells. Pernicious anaemia is associated with a slightly increased risk of stomach cancer.
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Barrett's Oesophagus
This condition was first described in 1950 as a change in the lining of the lower part of the oesophagus. There is an association between Barrett’s oesophagus and cancer of the upper part of the stomach. This can progress over time into an adenocarcinoma. Barrett's oesophagus occurs when the stomach contents, including bile and stomach acid, reflux into the oesophagus.
10% of patients with gastro-oesophageal reflux are affected by Barrett's oesophagus and of these, 1% per year develop a carcinoma. Overall, Barrett's oesophagus increases the risk of cancer by about 30 times.
Barrett's oesophagus is not associated with any specific symptoms and is usually discovered accidentally during other investigations.
Patients with Barrett’s oesophagus are treated with life-long acid suppression. Anti-reflux surgery may be advised in some cases to reduce the chances of progression to cancer.
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Preventing Stomach Cancer
The reduction in the incidence of cancer in the lower part of the stomach is probably due to changes in diet. Diets high in smoked and pickled foods and salted meat are best avoided.
A healthy diet high in fresh fruits and vegetables can also lower the risk of a number of cancers including stomach cancer. Vitamins A, C, and E and the mineral selenium may also reduce the risk of developing stomach cancer.
Obesity may add to the risk of a wide variety of cancers including stomach cancer. So reducing weight, by sticking to a healthy diet and taking regular exercise, should reduce the risk of stomach cancer.
Smoking increases the risk for many types of cancer. It is thought to be responsible for about one third of all cancer deaths as well as other causes of premature death.
There is considerable controversy about the need to treat people infected with H. pylori. Currently, there is insufficient evidence to be sure that treatment will prevent stomach cancer in people with this infection, but given the clear association, a common sense approach is to treat H. pylori infection.
Patients with Barrett’s oesophagus are treated with life-long acid suppression. Anti-reflux surgery may be advised in some cases to reduce the chances of progression to cancer.
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Symptoms of Stomach Cancer
Symptoms of stomach cancer:
- indigestion, particularly if you have not suffered from this before or if it does not go away quickly
- heartburn
- loss of appetite, especially if combined with a feeling of bloatedness after eating
- persistent vomiting
- blood in the stool or black stools (a sign of bleeding into the bowel)
- weight loss
- tiredness
However, none of these symptoms are unique to stomach cancer and may be due to a number of other illnesses. But anyone over the age of 50 who has these symptoms should seek advice from their doctor quickly.
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Diagnosing Stomach Cancer
Gastroscopy, looking inside the stomach with a flexible telescope, allows doctors to see the lining of the stomach, the size of any tumour that is present and to take samples for examination under a microscope.
Sometimes, the gastroscope has an ultrasound probe at the end, so that an ultrasound scan can be done of the stomach and surrounding structures, which helps assess whether the cancer has spread to other tissues.
A barium meal is a special X-ray test which used to be done very frequently but does not provide as much information as a gastroscopy.
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Treating Stomach Cancer
Surgery
Surgery is the main form of treatment for stomach cancer and usually involves removing the cancer and part or all of the stomach, and the lymph nodes near the stomach. This is known as a partial gastrectomy and lymph node dissection. If all the stomach is removed, it is a total gastrectomy.
Even if the cancer cannot be removed completely, surgery can prevent bleeding from the tumour and stop it from blocking food entering the rest of the gut.
Stomach surgery, particularly removal of the entire stomach, is major surgery and is not suitable for all patients.
External Beam Radiation
External beam radiation generated from machines outside the body uses high-energy rays to destroy cancer cells and is the type of radiation therapy often used to treat stomach cancer.
External beam radiation usually involves treatments given in small doses several days a week for a few weeks. The treatment itself is entirely painless but there is usually some damage to surrounding tissues.
Often radiotherapy is combined with chemotherapy (chemoradiation) in the treatment of stomach cancer. Drugs such as 5-Fluorouracil sensitise the cancer cells to the radiotherapy making it more effective.
Chemoradiation can be used before or after surgery. Recent studies have shown that this form of combined treatment gives better results than surgery alone.
Chemotherapy
Chemotherapy may be given as the main treatment for stomach cancer that has spread to other areas of the body, and may also be given with radiotherapy as the main treatment for stomach cancer (see above).
Biological Therapies – Monoclonal Antibodies
Monoclonal antibodies are used in the treatment of many forms of cancer. They target specific proteins necessary to the progression of the cancer, causing few side effects. In some patients with stomach cancer, proteins on the cancer cells can be targeted by specific monoclonal antibodies slowing cancer cell growth.
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Looking after Yourself
Radiotherapy for stomach cancer, as the sole treatment or in combination with surgery is effective in many cases but can cause a number of side effects. Some patients will not experience any side effects, whilst others may find several troublesome. Fortunately, many of these side effects disappear soon after the treatment ends and the symptoms can usually be treated, so if you do experience any problems it is important to mention them to your doctor or nurse, so they can give you the treatment you need.
Patients experience a range of symptoms during and after radiotherapy. Feeling sick, sometimes with vomiting, is relatively common and can be treated with medication if needed.
Diarrhoea can also occur and if necessary this can be treated with medication.
Reddening of the skin in the treatment area is not normally severe. Dry skin and soreness are best treated with the use of a non-perfumed, moisturising cream. In more troublesome cases a weak hydrocortisone cream helps to ease skin irritation and soreness.
These symptoms do diminish after treatment has finished and can be treated symptomatically if they occur. Radiotherapy also causes tiredness, which does gradually improve after the treatment has finished.
Whatever the problem, do not assume that nothing can be done about it – ask your doctor or nurse: do not just grin and bear it.
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Questions for your Doctor
Before making up your mind about the best treatment option for you, you will need information about your cancer, the treatments available in your area and what this will involve, what to expect from the treatment, what side effects you might experience and how these may change over time as well as what your doctors believe would be most effective in combating your cancer.
For different patients the answers will be different, so it is important to discuss all these issues with your doctor so that you make the right choice for you.
You will have your own questions but some issues you might want to raise are:
- What does the treatment involve?
- What are the benefits that I might get?
- How good are my chances of getting those benefits?
- Could having treatment make me feel worse? If so, in what way?
- Are there alternative treatments?
- What are the risks of the treatment?
- Are the risks minor or serious? How likely are they to happen?
- What care will I need after treatment?
- What happens if something goes wrong?
- What may happen if I don’t have the treatment?
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Conclusion
There is no one solution to the management of stomach cancer. Treatment for stomach cancer is improving all the time. For clinical and personal reasons particular treatments will suit some patients better than others so patients need comprehensive information so that they can make the right decision for them.
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