Background

In over 90% of patients with gastric cancer (cancer of the stomach), the malignant tumour in the stomach is known as a gastric adenocarcinoma. Other tumours, such as gastric 'MALT' lymphomas, are very rare. The incidence of gastric cancers varies widely in different parts of the world and it is particularly common, for example, in Japan, Chile and Iceland. In much of the Western world, the incidence of gastric cancer is falling steadily and, in the United States, the incidence of gastric cancer is now less than 8 / 100,000, although it is still the seventh most common cause of death from cancer. Stomach cancer is more common in older people: in the Western world, it is rare in people under the age of 50 years.

back to top

Causes

The causes of gastric cancer are not well understood. The World Health Organisation identified Helicobacter pylori (the stomach infection which also causes peptic ulcers) as a "Class I carcinogen" - that is, there is a definite association between gastric cancer and the presence of Helicobacter pylori.

Other research suggests that a diet which is low in vitamin C or high in salt may predispose to stomach cancer. However, there are not yet any studies to show that changes in diet will prevent stomach cancer.

There has been a handful of studies which suggest that the eradication (cure) of an H. pylori infection can result in the disappearance of the more rare form of stomach cancer - MALT tumours, without the use of any other therapies, such as chemotherapy. Recent research suggests that low-grade MALT tumours (restricted to the mucosa or top layer of the stomach lining) are more likely to disappear after H. pylori eradication than high-grade MALT tumours (those invading more deeply into the stomach lining or nearby lymph nodes).

There is still no evidence to suggest that the cure of H. pylori infection will treat or affect adenocarcinoma.

back to top

Symptoms

Stomach cancer does not produce any specific symptoms and it often does not cause any symptoms until it is relatively advanced. However, there are symptoms or changes which should lead to further tests although these symptoms can often occur in people who do not have cancer. The most common reasons for considering further tests would be someone who has:

- bleeding from the stomach or intestines (hematemesis - vomiting blood, melena - passing blood in the stool, anemia - low hemoglobin levels in the blood),

- recurrent vomiting

- unintended weight loss

- difficulty swallowing (food seems to stick or catch)

- a mass or lump in the abdomen.

back to top

Investigations

If stomach cancer is suspected, there are number of tests which may be performed. Some tests (e.g. endoscopy, barium X-rays) are intended to find or confirm the cancer, some are intended to see if the cancer has spread (e.g. ultrasound, CT scan) and others are intended to see if the cancer has caused other problems (e.g. blood tests).

Endoscopy
This provides a direct view of the lining of the esophagus, stomach and duodenum; if an area looks abnormal or suspicious, biopsies (small samples of the lining of the stomach) can be taken and sent to the laboratory for testing. It also allows the physician to detect other conditions such as esophagitis, peptic ulcer, celiac disease, gastric lymphoma, which may require treatment. Endoscopy is the most accurate test for diagnosing gastric cancer.

Barium X-ray (Upper GI Series)
This provides X-ray pictures in which barium can outline irregularities of the esophagus, stomach or duodenum; often, these appearances are very suggestive of cancer or ulcers but this test does not allow biopsies to be taken to confirm the diagnosis. Barium X-rays are not as good as endoscopy at detecting small or early cancers and, if a suspicious area is seen on the X-ray, a follow-up endoscopy is required to make a firm diagnosis.

Abdominal Ultrasound
This uses high frequency sound waves to detect abnormal areas in the liver, such as cancer deposits (secondaries or metastases) or abnormal masses in the stomach or nearby lymph nodes. This test is not used to diagnose stomach cancer.

Abdominal CT Scan
This uses X-rays to detect abnormalities similar to those detected by ultrasound - abnormal areas in the liver, such as cancer deposits (secondaries or metastases) or abnormal masses in the stomach or nearby lymph nodes. It can be more accurate in detecting small abnormalities but it is also a more complicated, longer and more expensive test than ultrasound.

Blood tests
There are no blood tests to diagnose stomach cancer. However, blood tests are important to test for anemia and liver abnormalities which may develop in someone with stomach cancer.

back to top

Treatment

The main treatment for stomach cancer is surgery. In Japan, where there are screening programs to detect early stomach cancer, surgical removal of the cancer is often successful but, in the rest of the world, surgery is less often successful because the cancers are usually more advanced. Sometimes, surgery is performed to bypass the cancer, if the cancer has blocked the passage of food through the stomach and is causing vomiting.

Chemotherapy and radiotherapy have not produced great improvements in treatment although a small proportion of patients may benefit.

back to top

Barrett's Esophagus

Barrett's Esophagus is a condition that develops in some people who have chronic gastroesophageal reflux disease (GERD) or inflammation of the esophagus (esophagitis). In Barrett's esophagus, the normal cells that line the esophagus, called squamous cells, turn into a type of cell not usually found in humans, called specialized columnar cells. Damage to the lining of the esophagus--for example, by acid reflux from GERD--causes these abnormal changes.

People who have had regular or daily heartburn for more than 5 years may be at risk for Barrett's esophagus and should discuss the possibility with their doctor. Symptoms include waking during the night because of heartburn pain, vomiting, blood in vomit or stool, and difficulty swallowing. Some people do not have symptoms.

Diagnosis involves an endoscopy to look at the lining of the esophagus and a biopsy to examine a sample of tissue. To do an endoscopy, the doctor gently guides a long, thin tube called an endoscope through the mouth and into the esophagus. The scope contains instruments that allow the doctor to see the lining of the esophagus and to remove a small tissue sample, called a biopsy. The biopsy will be examined in a lab to see whether the normal squamous cells have been replaced with columnar cells.

Once the cells in the lining of the esophagus have turned into columnar cells, they will not revert back to normal. In other words, at this time, there is no cure for Barrett's esophagus. The goal of treatment is to prevent further damage by stopping any acid reflux from the stomach. Medications that are helpful include H2 receptor antagonists (or H2 blockers) and proton pump inhibitors, which reduce the amount of acid produced by the stomach. Examples of H2 blockers are cimetidine, ranitidine, and famotidine; the drugs omeprazole and lansoprazole are proton pump inhibitors. If these medications do not work, surgery to remove damaged tissue or a section of the esophagus itself may be necessary. Fundoplication is the name of the surgery to remove part of the esophagus and attach the stomach to the remaining section.

Sometimes the damaged lining of the esophagus becomes thick and hardened, causing strictures, or narrowing of the esophagus. Strictures can interfere with eating and drinking by preventing food and liquid from reaching the stomach. Strictures are treated by dilation, in which an instrument gently stretches the strictures and expands the opening in the esophagus.

About 5 to 10 percent of people with Barrett's develop cancer of the esophagus. Because of the cancer risk, people with Barrett's esophagus are screened for esophageal cancer regularly.

back to top

Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome is a rare disorder that causes tumors in the pancreas and duodenum and ulcers in the stomach and duodenum. The pancreas is a gland located behind the stomach. It produces enzymes that break down fat, protein, and carbohydrates from food, and hormones like insulin that break down sugar. The duodenum is the top part of the small intestine.
The tumors are cancerous in 50 percent of cases. They secrete a substance called gastrin that causes the stomach to produce too much acid, which in turn causes the stomach and duodenal ulcers (peptic ulcers). The ulcers caused by Zollinger-Ellison syndrome are more painful and less responsive to treatment than ordinary peptic ulcers. What causes people with Zollinger-Ellison syndrome to develop tumors is unknown, but the cause may be an abnormal tumor suppressor gene.
Zollinger-Ellison syndrome usually occurs in people between ages 30 and 60. Symptoms include signs of peptic ulcers: gnawing, burning pain in the abdomen; diarrhea; nausea; vomiting; fatigue; weakness; and weight loss. Physicians diagnose Zollinger-Ellison syndrome through blood tests to measure levels of gastrin. They may check for ulcers by taking x-rays of the stomach and duodenum or by doing an endoscopy, which involves looking at the lining of these organs through a lighted tube.

Medications used to reduce stomach acid include cimetidine, ranitidine, famotidine, and omeprazole. Surgery to treat peptic ulcers or to remove tumors in the pancreas or duodenum are other treatment options. In serious cases, surgery to remove the entire stomach may be necessary.

back to top