Stomach cancer
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Stomach cancer begins in the glandular tissue of the stomach and is also known as gastric cancer. The stomach is only one of many organs in the abdomen that can develop cancer.
The stomach is a sack-like organ that holds food and mixes it with gastric juice to begin the process of digestion. It is divided into 5 different sections, cancer can start in any of these areas. Most of the time cancer starts in the mucosa, the innermost layer where the stomach acid and digestive juices are made.
Stomach cancer grows slowly over many years and can spread in several different ways. It can grow through the wall of the stomach and into nearby organs. It can also spread to the lymph nodes via the lymph system. When stomach cancer is more advanced, it will travel through the bloodstream and form deposits of cancer cells in organs such as the liver, lungs, and bones.
Age
There is a sharp increase in stomach cancer after the age of 50.
Gender
Stomach cancer is about twice as common in men as it is in women.
Ethnicity
The highest rates of stomach cancer are seen in Asian populations and Pacific Islanders.
Diet
A diet high in smoked foods, salted fish and meats, pickled vegetables, and certain foods high in starch and low in fibre can increase the risk of stomach cancer.
Family history of stomach cancer
People with several close relatives who have had stomach cancer are more likely to develop the disease.
Bacteria infection
There is some evidence that infection with bacteria called Heliobacter pylori could be a major cause of stomach cancer. Long-term infection with these bacteria can lead to inflammation and damage to the inner layer of the stomach, a possible precancerous change. This bacterium is also linked to some types of lymphoma of the stomach. However most people who carry this germ in their stomach never develop cancer.
Alcohol
There is no conclusive evidence linking alcohol use to stomach cancer. However it is recommended that alcohol is drunk in moderation.
Tobacco
Smoking almost doubles the risk of stomach cancer.
Earlier stomach surgery
Stomach cancer is more likely to occur in people who have had part of their stomach removed to treat other problems such as ulcers.
Type A Blood
People with type A blood have a higher risk of developing stomach cancer, it is not known why.
Stomach polyps
Polyps are small mushroom-like growths of the lining of the stomach. Most types of polyps do not increase the risk of stomach cancer. However one type, adenomatous polyps, can sometimes develop into stomach cancer.
Diet
Increased use of refrigeration for food storage and changes in diet has helped lower the rate of stomach cancer. Eating whole grain products, and fresh fruits and vegetables that contain vitamins A and C appear to lower the risk of stomach cancer.
It is recommended that at least 5 servings of fruits and vegetables should be eaten each day as well as servings of whole grain foods like breads, cereals, pasta, rice, and beans. Red meats, especially those high in fat or processed, should be limited.
It is recommended that Alcohol is drunk in moderation.
Tobacco
Stopping smoking reduces the risk of stomach cancer.
Aspirin
One study has reported that aspirin and other non-steroidal anti-inflammatory medicines may reduce the risk of developing stomach cancer.
The Japanese who have the highest rates of stomach cancer in the world have pioneered mass screening for stomach cancer. The screening programme has been a success and early diagnosis has increased patient survival.
However Europe has a much lower incidence rate making mass screening inappropriate. In Europe there is currently no screening programme for detecting stomach cancer.
Early stomach cancer does not usually produce symptoms. Later signs and symptoms of stomach cancer can include:
- Unintended weight loss and lack of appetite
- Abdominal pain
- Swelling of the abdomen
- A sense of fullness just below the chest bone after eating a small meal
- Heartburn, indigestion, or ulcer-type symptoms
- Nausea
- Vomiting, with or without blood
Diagnosis of stomach cancer can include the following:
Physical examination
The doctor will feel the abdomen to see if there is any swelling that might indicate a tumour. They will also feel to see if the liver is enlarged which could mean that cancer has spread there.
Upper Endoscopy
A thin, flexible, lighted tube is placed down the throat. With this tube the doctor can see the lining of the oesophagus, stomach, and the first part of the small intestine. Tissue samples can be removed and looked at under a microscope to see if cancer is present and what type it is.
Upper GI (gastrointestinal)
A liquid drink is taken containing barium that coats the lining of the oesophagus, stomach, and first part of the small intestine. After drinking the liquid a thin tube is swallowed and air is pumped into the stomach. This makes the barium coating very thin so that even small abnormalities will show up. Then several x-rays are taken.
Ultrasound
Sound waves are used to produce pictures of internal organs. The picture can be taken externally or through a probe placed into the stomach through the mouth or nose. The ultrasound can help tell how far the cancer has spread within the stomach or into nearby tissues and lymph nodes.
CT scan (computed tomography)
This test uses a special x-ray machine that takes pictures from many angles. The pictures are combined by a computer to produce detailed cross-sectional images. The CT scan can help show if and where stomach cancer has spread, especially to the liver.
PET scan (positron emission tomography)
A special kind of radioactive sugar is injected into the patient’s vein. The sugar collects in areas that have cancer and a scanner can spot these areas. This test is useful for finding cancer that has spread beyond the stomach.
MRI scan (magnetic resonance imaging)
Like CT scans, MRI displays a cross-section of the body. The MRI uses powerful magnets instead of radiation.
Chest x-rays
These can be used to tell if the cancer has spread to the lungs and other organs.
Laparoscopy
A thin, flexible tube with a tiny video camera on the end is placed into the patient’s side through a small incision. The doctor can use this to see if the cancer has spread or after the operation to see if the cancer has been removed.
Blood and Laboratory tests
Blood may be taken to look for signs of anaemia. A fecal occult blood test may be taken which looks for small amounts of blood in the stool.
Treatment depends on the size, location and type of stomach cancer and how advanced the cancer has become. The most common types of treatments for stomach cancer are surgery, chemotherapy and radiotherapy, or a combination of these treatments in varying order.
Surgery
Depending on the type and stage of the cancer, surgery might be used to remove the cancer and the part of the stomach affected. The surgeon will try to leave behind as much normal stomach as possible. The lymph nodes and some of the fatty tissue around the stomach are often removed as well. If the cancer has spread beyond the stomach to the spleen, it will be removed too.
There are 3 main types of surgery for stomach cancer:
Endoscopic mucosal resection
The cancer is removed through an endoscope by cutting it out. This can only be done for very early cancers where the chance of spread to the lymph nodes is very low.
Subtotal gastrectomy
Only part of the stomach is removed, sometimes along with the first part of the small intestine. This surgery can be used if the cancer is in the lower part of the stomach close to the intestines.
Total gastrectomy
The entire stomach is removed. This surgery can be used if the cancer is in the middle or upper part of the stomach. The surgeon will try to make a new "stomach" out of intestinal tissue.
Side effects of surgery
Surgery for stomach cancer is a difficult procedure and there may be serious complications. These could include bleeding from the surgery, blood clots, and damage during the operation to nearby organs such as the gallbladder and the pancreas. Rarely, the connections between the ends of the stomach and oesophagus or small intestine may not hold together completely and leak.
Other side effects may develop after recovery from surgery. These could include heartburn, abdominal pain, especially after eating, and shortages of some vitamins. The stomach is important in helping the body absorb certain vitamins. If some parts of the stomach are removed, the doctor will prescribe vitamin supplements. After stomach surgery, most people will need to change their diets, eating smaller, more frequent meals.
Chemotherapy
Chemotherapy is the use of drugs to treat cancer. Chemotherapy can be given to treat stomach cancer before or after surgery. Usually a combination of chemotherapy drugs are given into a vein or by mouth. Once the drugs enter the bloodstream they spread throughout the body. This treatment works well when the cancer has spread beyond the stomach. The drugs can also be given directly into the abdomen which aims the drugs right at the cancer cells and limits the amount reaching the rest of the body. This helps reduce side effects.
There is also some evidence that chemotherapy together with radiation therapy may delay the cancer coming back and extend the life of people with advanced stomach cancer.
Side effects of chemotherapy
While chemotherapy drugs kill cancer cells, they also damage some normal cells. The side effects will depend on the type of drugs given, the amount taken, and how long the treatment lasts. Side effects might include the following:
- Nausea and vomiting
- Loss of appetite
- Hair loss
- Hand and foot rashes
- Kidney or nerve damage
- Mouth sores
- An increased chance of infection
- Bleeding or bruising after minor cuts
- Tiredness
Most side effects go away when treatment ends.
Radiation Therapy
Radiation therapy uses high energy x-rays to kill or shrink cancer cells. The radiation may come from outside the body or from radioactive materials placed directly into or near the tumour. Internal radiation therapy is most often used to treat stomach cancer.
After surgery, radiation therapy can be used to kill very small areas of cancer that cannot be seen and removed during surgery. Some studies suggest that radiation, especially when combined with chemotherapy, can delay or prevent the cancer from coming back after surgery and may help people to live longer.
Side effects of radiation therapy
Radiation therapy may cause side effects but is generally relatively easy to tolerate. Side effects from radiation therapy can include mild skin problems, nausea, vomiting, diarrhoea, or fatigue. These usually go away a few weeks after treatment is finished.
World wide
- Stomach cancer is the fourth most frequent cancer in the world.
- There are 800,000 new cases annually.
- Japan and Korea have the highest rates of stomach cancer. It is the most common cancer in men and women in Japan.
- Intermediate rates occur in South America and Eastern Europe.
- There are generally low rates in Africa.
Europe
- The highest rates are recorded in Portuguese men and woman.
- Italy has the second highest rates for men and women.
- The Lowest rates are recorded in Danish men and woman.
UK
- Stomach cancer is the sixth most common cancer in the UK
- There are 10,000 new cases each year
- It is the fifth most common cancer in men
- It is the ninth most common cancer in woman
Trends
In most countries throughout the world stomach cancer incidence is declining. The global decrease has occurred without any significant improvements in diagnosis or treatment.
Survival
Survival rates continue to improve and are considerably higher for younger patients. The challenge is to increase the number of patients diagnosed at an early stage of stomach cancer which will improve the chances of survival.
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