胃癌-Stomach (Gastric) Cancer

What is the stomach?

The stomach is is in the upper abdomen. It is part of the gastrointestinal tract (the gut). It lies in the upper part of the abdomen, just below the ribs. When we eat, food passes down the oesophagus (gullet) into the stomach.

The stomach makes acid which is not essential, but helps to digest food. The muscles in the wall of the stomach contract to mix up the food with the acid.

Food then passes into the duodenum (the first part of the small intestine). Here food mixes with enzymes (chemicals) which come from the pancreas and lining of the gut. The enzymes break down (digest) the food.

Digested food is then absorbed into the body from the small intestine.

What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.

A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. As they grow, malignant tumours invade into nearby tissues and organs which can cause damage.

Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook. See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.

What is stomach cancer?

Stomach cancer is sometimes called gastric cancer. World-wide it is one of the most common cancers. For example, it is common in Japan and China. It is less common in the UK. Stomach cancer is more common in men than women and tends to occur mainly in older people. Most cases are in people over the age of 45.

Adenocarcinoma of the stomach
In most cases, stomach cancer begins from a cell which is on the inside lining of the stomach (the mucosa). This type of stomach cancer is called adenocarcinoma of the stomach. As the cancer cells multiply:

• The tumour may invade deeper into the wall of the stomach. In time it may pass through the wall of the stomach and invade nearby organs such as the pancreas or liver.
• The tumour may spread up or down the stomach into the oesophagus (gullet) or small intestine.
• Some cells may break off into the lymph channels or bloodstream. The cancer may then spread to nearby lymph nodes or spread to other areas of the body (metastasise).

Other types of stomach cancer
There are some less common and rare types of stomach cancer which include:

• Lymphoma. These are cancers which arise from lymphatic tissue within the wall of the stomach.
• Sarcomas. These are cancers which arise from muscle or connective tissue within the wall of the stomach
• Carcinoid cancers. These are cancers which arise from cells in the stomach lining which make hormones.

The rest of this leaflet only discusses adenocarcinoma of the stomach.

What causes stomach cancer (adenocarcinoma of the stomach)?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

Many people develop stomach cancer for no apparent reason. However, certain 'risk factors' increase the chance that stomach cancer may develop. These include:

• Ageing. Stomach cancer is more common in older people. Most cases are in people over the age of 45.
• If a close relative has had stomach cancer. Stomach cancer is also more common in people with blood group A. (So, there is probably some genetic factor.)
• Diet is probably a factor:
  • Countries such as Japan where people eat a lot of salt, pickled and smoked foods have a high rate of stomach cancer.
  • Eating a lot of fruit and green vegetables is thought to reduce the risk.
• Long term infection of the stomach lining with a bacterium called H pylori. (This infection is very common in the UK, and most people with H pylori infection do not develop stomach cancer. But it does have some small risk or causing stomach cancer. See separate leaflet called 'H Pylori and Stomach Pain'.)
• If you have pernicious anaemia there is a small increased risk.
• Gender. Stomach cancer is twice as common in men than women.
• If you have had part of your stomach removed in the past for any reason. For example, if you had part of your stomach removed to treat a stomach ulcer or some other condition.

What are the symptoms of stomach cancer?

When a stomach cancer first develops and is small it usually causes no symptoms. Some do not cause symptoms until they are quite advanced. Initial symptoms may include:

• Pain or discomfort in the upper abdomen, especially after eating.
• Indigestion. (Note: most people who have indigestion do not have stomach cancer.)
• Feeling sick, off food. Some people have a sense of fullness after eating.
• Vomiting blood.
• You may pass blood out with your faeces (motions). You may not notice bleeding if small amounts of blood passes out with your faeces. A lot of bleeding from the stomach can turn your faeces black.

As the cancer grows in the stomach, symptoms may become worse and include

• The same symptoms as above, but more severe.
• You may feel generally unwell, tired, or lose weight.
• You may become anaemic if the tumour regularly bleeds.
• The cancer may grow very large and cause a 'blockage' to food and drink.

If the cancer spreads to other parts of the body, various other symptoms can develop.

If any of the above symptoms develop for more than a week or so, then see your doctor. All the above symptoms can be due to other conditions, so tests are needed to confirm stomach cancer.

How is stomach cancer diagnosed and assessed?

Initial assessment and gastroscopy
If a doctor suspects that you may have stomach cancer, he or she will examine you to look for signs such as a lump in your abdomen, anaemia, etc. The examination is often normal, especially if the cancer is at an early stage. Therefore, a gastroscopy (endoscopy) is usually arranged.

A gastroscope (endoscope) is a thin, flexible, telescope. It is passed through the mouth, into the oesophagus and down towards the stomach and duodenum. The endoscope contains fibre optic channels which allows light to shine down so the doctor can see inside. See separate leaflet for details about gastroscopy.

Biopsy - to confirm the diagnosis
A biopsy is when a small sample of tissue is removed from a part of the body. The sample is then examined under the microscope to look for abnormal cells. When you have a gastroscopy, if anything abnormal is seen then the doctor or nurse can take a biopsy. This is done by passing a thin grabbing instrument down a side channel of the gastroscope.

Assessing the extent and spread
If you are confirmed to have stomach cancer, further tests may be done to assess if it has spread. For example, a barium meal X-ray, a CT scan, an MRI scan, an ultrasound scan, laparoscopy, or other tests. (There are separate leaflets which describe each of these tests in more detail.) This assessment is called 'staging' of the cancer. The aim of staging is to find out:

• How much the tumour in the stomach has grown, and whether it has grown partially or fully through the wall of the stomach.
• Whether the cancer has spread to local lymph nodes.
• Whether the cancer has spread to other areas of the body (metastasised).

By finding out the stage of the cancer it helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See separate leaflet called 'Cancer Staging and Grading' for details.

What are the treatment options for stomach cancer?

Treatment options which may be considered include surgery, chemotherapy (and sometimes radiotherapy). The treatment advised for each case depends on various factors such as the stage of the cancer (how large the cancer is and whether it has spread), and your general health.

You should have a full discussion with a specialist who knows your case. They will be able to give the pros and cons, likely success rate, possible side-effects, and other details about the various possible treatment options for your type of cancer.

You should also discuss with your specialist the aims of treatment. For example:

• Treatment may aim to cure the cancer. Some stomach cancers can be cured, particularly if they are treated in the early stages of the disease. (Doctors tend to use the word 'remission' rather than the word 'cured'. Remission means there is no evidence of cancer following treatment. If you are 'in remission', you may be cured. However, in some cases a cancer returns months or years later. This is why doctors are sometimes reluctant to use the word cured.)
• Treatment may aim to control the cancer. If a cure is not realistic, with treatment it is often possible limit the growth or spread of the cancer so that it progresses less rapidly. This may keep you free of symptoms for some time.
• Treatment may aim to ease symptoms. If a cure is not possible, treatments may be used to reduce the size of a cancer which may ease symptoms such as pain. If a cancer is advanced then you may require treatments such as nutritional supplements, painkillers, or other techniques to help keep you free of pain or other symptoms.

Surgery
Removing the tumour may be curative if the cancer is in an early stage. The common operation is to cut out the affected part of the stomach. Sometimes the whole of the stomach is removed. This is a major operation and carries some risk.

Even if the cancer is advanced and a cure is not possible, some surgical techniques may still have a place to ease symptoms. For example, a blockage may be eased by removing part of the stomach, or by using laser surgery, or by a bypass operation.

Chemotherapy
Chemotherapy is a treatment of cancer by using anti-cancer drugs which kill cancer cells, or stops them from multiplying. See separate leaflet called chemotherapy for more details.

When chemotherapy is used in addition to surgery it is known as 'adjuvent chemotherapy'. For example, following surgery you may be given a course of chemotherapy. This aims to kill any cancer cells which may have spread away from the primary tumour. Sometimes, adjuvant chemotherapy is given before surgery to shrink a large tumour so that surgery is easier. 醫(yī).學 全在.線提供www.med126.com

Radiotherapy
Radiotherapy is a treatment which uses high energy beams of radiation which are focussed on cancerous tissue. This kills cancer cells, or stops cancer cells from multiplying. (There is a separate leaflet which gives more details about radiotherapy.) Radiotherapy is not commonly used to treat stomach cancer. It is sometimes used to reduce the size of a particular part of the cancer which is causing symptoms.

What is the prognosis (outlook)?

Without treatment, a stomach cancer is likely get larger, and spread to other parts of the body. If it is diagnosed and treated at an early stage (before growing through the wall of the stomach or spreading to lymph nodes or other areas of the body) then there is a good chance of a cure with surgery. Unfortunately, most cases in the UK are not diagnosed at an early stage.

If the cancer is diagnosed when it has grown through the wall of the stomach, or spread to other parts of the body, a cure is less likely. However, treatment can often slow down the progression of the cancer.

The treatment of cancer is a developing area of medicine. New treatments continue to be developed and the information on outlook above is very general. The specialist who knows your case can give more accurate information about your particular outlook, and how well your type and stage of cancer is likely to respond to treatment.