Stomach (Gastric) Cancer
Thankfully, stomach cancer (also referred to as gastric cancer) has become much less common in the USA and other industrialized countries over the last fifty years or so. The reasons for this are not fully understood. Nevertheless, this is a serious condition and it remains extremely common in some parts of the world, including China, Japan, and parts of South America. It occurs more commonly in men, especially after the age of fifty years.
What causes cancer of the stomach?
No single cause for stomach cancer has been identified. However, a number of possible important risk factors are known. Some of these include:
- diets rich in salted or smoked foods
- some foods containing nitrites; these chemicals can be converted to more harmful compounds (carcinogens) by bacteria in the stomach
- heavy alcohol intake
- lack of vitamin C, fruits and vegetables
- Helicobacter pylori
- family history
In recent years studies have reported that infection with Helicobacter pylori (HP) may increase the risk of stomach cancer threefold to sixfold. This data has come from large population studies comparing the rates of HP infection in patients with stomach cancer to those without stomach cancer. It has been estimated that HP infection may actually be responsible for approximately 60% of all cases of stomach cancer ... but this is controversial.
A great deal of research is currently underway to find out more about the role that this bacteria may play in causing stomach cancer. At present, however, the link has not been proven and there is no evidence that offering antibiotic therapy to healthy people who carry the infection will reduce the risk of developing stomach cancer.
The risk of stomach cancer is also slightly higher in close relatives of patients with the disease but no specific genetic abnormality has been identified. This increased risk in family members may be the result of similar diet and smoking habits, etc.
Can stomach cancer be prevented?
In Japan, where stomach cancer is much more common than in the USA, endoscopy screening of healthy people over forty years of age has been able to detect tiny, early tumors before they cause symptoms. Surgery is much more successful when the cancer is at an early stage and improved survival has been reported.
In Western countries where stomach cancer is less common, screening is unlikely to be as effective and would be extremely expensive. If Helicobacter pylori infection is proven to be important then it may be possible to prevent stomach cancer by treating the infection.
What are the symptoms and signs of stomach cancer?
In the early stages of stomach cancer, when the tumor is still small, there are usually no symptoms. However, patients at a more advanced stage usually complain of indigestion and upper abdominal pain.
Other likely symptoms include:
- significant weight loss
- loss of appetite,
- nausea and vomiting
- gastrointestinal bleeding (anemia)
- difficulty swallowing (dysphagia) usually caused by a blockage between the esophagus and stomach
Occasionally, the condition only presents itself when the disease is advanced with evidence of a tumor spreading to the liver or abdominal cavity. This may cause a build-up of fluid in the abdomen.
How is stomach cancer diagnosed?
An upper endoscopy (EGD) is the most important investigative tool in the diagnosis of stomach cancer. An EGD should be done promptly in patients with indigestion or heartburn that persists for more than a few weeks or which does not respond to treatment, especially in those over the age of 40-45 years.
At endoscopy, the inner lining of the stomach (mucosa) can be carefully inspected and biopsies of any suspicious or abnormal areas can be taken.
Sometimes it is not possible to tell whether a gastric ulcer is benign or malignant from the appearances alone, and multiple biopsies are usually needed. All patients with a gastric ulcer that is thought to be benign should undergo a repeat examination four to six weeks after treatment to ensure that the ulcer has healed properly.
Stomach Cancer Assessment
Once the pathologist has confirmed the diagnosis of cancer, further investigations are then carried out to hopefully answer the following questions:
- Has the tumor spread through the wall of the stomach to involve adjacent organs?
- Has the disease spread to the liver?
This assessment is necessary to determine whether or not the tumor can be removed surgically.
A CT scan is the most important investigation for this and usually gives accurate information. Occasionally, however, tiny deposits of tumor have spread (like seeds) throughout the abdomen and are not visible on the CT scan.
For this reason, surgeons sometimes wish to perform a laparoscopic procedure before deciding whether or not to operate. In this technique, the patient is given brief general anesthetic and the surgeon inspects the abdominal cavity carefully with a telescope that is passed through a small incision in the abdominal wall.
What treatments are available for stomach cancer?
Surgery to remove the tumor is the only means of curing stomach cancer. A cure can be achieved in 80% or more of patients with tiny early stomach cancers; unfortunately, such cases are uncommon outside Japan. For the majority of patients, surgery involves removing part or all of the stomach, depending upon the exact location of the tumor.
Surgery may also be necessary in patients who cannot be cured, as this may be the only means of relieving distressing symptoms such as a blockage of the stomach.
Chemotherapy and radiotherapy treatment given after surgery are not very effective in preventing recurrence of the disease or improving survival. Recently, however, better results have been obtained by giving chemotherapy pre-operatively.
For patients with inoperable tumors, it is sometimes possible to control symptoms (i.e. difficulty swallowing or recurrent bleeding) by laser therapy performed using an endoscope. Similarly, difficulty swallowing or an obstruction between the stomach and duodenum can sometimes be controlled by inserting an expandable metallic tube (stent) through the blocked region to hold it open. Some improvement in symptoms may also be obtained with chemotherapy.
One of the bewildering aspects of a cancer diagnosis is the many words that are used to describe the condition. Here are a few that we thought you should know:
- Carcinoma — an early form of cancer that has not spread, or a pre-cancer
- Dysplasia — the earliest form of a pre-cancerous lesion
- Histology — microscopic study of the anatomy of cells
- Malignant — a medical condition that becomes progressively worse
- Metastasis — term used to indicate that a disease has spread to another organ
- Neoplasm — term used for an abnormal mass. (A tumor is a neoplasm.)
- Staging — the extent to which a cancer has developed or spread