Stomach Cancer explained
The stomach is a storage organ for food. When you eat your meals, food stays in the stomach for a while, and this is where digestion starts. Food is churned up, and mixed with acid until it is partly liquefied, when it is passed on into the rest of the bowel for further digestion, and for the nutrients to be absorbed. The stomach is actually a large hollow muscle, whose movement is controlled by nerves and hormones, triggered by the sight, smell or sound of food.
The incidence of stomach cancer has decreased rapidly over the last fifty years, probably due to improved diet and living conditions. About 10,000 new cases per year are diagnosed in England and Wales. It is more common in some parts of the world such as Japan, China, Eastern Europe and Central and South America. In the UK lung, breast and colon cancer are seen much more frequently. Stomach cancer is much more common in older people, but sometimes affects patients in their 30s or 40s.
Cancers of the stomach are not all the same, and it is likely that there are different causes. Certain conditions of the stomach may predispose to stomach cancer. These include pernicious anaemia, chronic inflammation, ulcers and large polyps. Smoking, and a high salt or high nitrate/nitrite diet may also cause problems. Nitrites are found in cured meats, pickled fish, and may also originate in fertilisers. Helicobacter pylori is a bacterium which can infect the stomach. This may lead to ulcers, and is also thought to predispose to stomach cancer. Stomach cancer does not often run in families; a family history of stomach cancer is found in less than one in ten patients with the condition.
The genes that control the growth of stomach cells become disorganised, making the cells grow quickly, and beyond their normal boundaries. As the tumour enlarges, the cells grow through the lining of the stomach, and can invade adjacent structures such as fat or the pancreas. Some cells can break away, travel up the bloodstream and go to other sites such as the liver or lungs. These are known as secondaries, or metastases.
A healthy diet containing fruit, vegetables and some animal fat and protein may help to prevent stomach cancer. The widespread use of frozen rather than pickled foods may have influenced the reduction in the incidence of the problem over the last fifty years.
The earlier a diagnosis can be made, the more likely it is that the problem can be cured. The longer a cancer is present in the stomach, the more likely it is that it will spread to other parts of the body such as lymph glands and the liver.
Stomach cancer can present in many different ways depending on which part of the stomach is involved. Indigestion (pain or discomfort in the upper abdomen related to eating or drinking), and loss of appetite are common, and associated with weight loss. If the cancer is at the top of the stomach near the gullet, it may cause difficulty with swallowing food. If it is at the bottom of the stomach, it may cause vomiting of food. Cancers can sometimes bleed, leading to symptoms of anaemia such as tiredness and shortness of breath.
Many of the symptoms of stomach cancer are similar to those of a benign ulcer. It is very important that any new occurrences of the symptoms listed above are reported to your doctor if you are over 40.
Occasionally a lump can be felt in the abdomen, but other tests are always needed. • Endoscopy (video examination of the stomach). This is a simple test carried out under local anaesthetic. A small sample of tissue is taken for examination under a microscope (histology) and a test is taken for Helicobacter pylori, a bacterium which can infect the stomach and is thought to increase the risk of stomach cancer.
- CT scan – this is an X-Ray which takes 3 dimensional pictures of the chest, abdomen and pelvis areas. It gives information about the stomach itself, and also about other areas that disease may have spread to.
If the tests show that you have stomach cancer, you will be referred to a cancer specialist – usually a surgeon – for further assessment. It is likely that you will have a staging laparoscopy. Under a general anaesthetic, a small telescope is passed through the belly button into the abdomen to examine the stomach and other areas closely. The results of your tests will then be discussed by a group of cancer experts, and a decision will be made on the best form of treatment.
Once checks have been made that it has not spread anywhere else, most stomach cancers will be removed by surgery. Either a part of the stomach or the whole stomach is removed, with lymph glands that are close by. The stomach or gullet is then joined to the bowel (anastomosis). Once the cancer has been removed it is examined closely under the microscope to decide exactly what stage it is at. If the cancer is an early one that has not spread through the stomach wall, then no further treatment may be necessary. If the cancer has spread through the wall, or involved lymph glands you may be offered further treatment such as chemotherapy, radiotherapy or a combination of both. Sometimes chemotherapy is given before surgery.
You will stay in hospital for about 10 days after your operation. You will take 6 to 8 weeks to recover fully. You will see a dietician who will advise you on the best foods to eat. The main advice will be to eat a balanced diet, little and often. All the test results will be discussed to decide if any further treatment is necessary. You will be told the results when you come back to see your surgeon about a month after surgery. You will be seen regularly in clinic over the months and years after your treatment, and will be offered regular blood tests. Sometimes further scans and endoscopies are needed to see if the cancer has come back. If the problem does recur, it can be treated again, usually with chemotherapy or radiotherapy.
If the cancer has already spread beyond the stomach to other structures when it is diagnosed, it is sometimes not amenable to surgery. In this case it is treated by chemotherapy, and sometimes radiotherapy. There are some new minimal access (endoscopic) ways of dealing with problems such as blockages, by using fine mesh tubes called stents. Cancer can sometimes become advanced even after treatment, and careful follow up is usually necessary.
A healthy lifestyle, with a balanced diet and a positive mental attitude are good advice. Regular medical follow up is also important.
Only about 4% of patients with stomach cancer have a close relative with the same problem. It is therefore not likely that other members of your family will need to be screened. They should however be advised on a healthy diet.
In some areas of the world such as Japan, the incidence of stomach cancer is so high that endoscopic screening is carried out on everyone. In the UK, the incidence of the problem is a lot lower, so screening is not necessary.
Recent research into the treatment of stomach cancer has centred around how medical treatment may improve the results of surgery. Treating some patients with chemotherapy before surgery may improve long term outcome, and some patients with more advanced disease may benefit from post-operative chemotherapy, sometimes with radiotherapy as well. Trials are in progress to study these factors in more detail.