Stomach cancer

The oesophagus and stomach are part of the upper gastrointestinal (GI) tract, which is part of the digestive system. The digestive system helps the body break down food and turn it into energy.

The oesophagus (food pipe or gullet) is a long, muscular tube that delivers food, fluids and saliva from the mouth and throat to the stomach. A valve (sphincter) at the end of the oesophagus stops acid and food moving from the stomach back into the oesophagus.

The stomach is a hollow, muscular organ in the upper left part of the abdomen, located between the end of the oesophagus and the beginning of the small bowel (small intestine). The stomach expands to store food that has been swallowed. It also helps with the absorption of some vitamins and minerals.

In the stomach, acidic (gastric) juices are released from glands in the stomach lining (mucosa). These juices break down food into a thick fluid, which then moves into the small bowel. In the small bowel, nutrients from the broken-down food are absorbed into the bloodstream. The waste matter moves into the large bowel (large intestine), where fluids are reabsorbed back into the body. The solid waste matter is passed out of the body as a bowel movement.

The stomach and oesophagus

The different layers of tissue (known as the wall) in the stomach include:

• mucosa (moist innermost layer) – contains glands that produce gastric fluids to start breaking down food
• submucosa (supports the mucosa) – provides blood and nutrients to the stomach
• muscle layer – known as the muscularis externa, it produces muscle contractions to help break down food and push it into the small bowel in a controlled way
• outer layer – known as the serosa, this is a smooth membrane that surrounds the stomach.

The exact causes of stomach cancer are unknown, but the factors listed below may increase your risk. However, having one or more of these risk factors does not mean you will develop cancer. Known risk factors for stomach cancer include:

• older age (being over 60)
• infection with Helicobacter pylori (H. pylori), a type of bacteria found in the stomach
• having had a subtotal gastrectomy to treat non-cancerous conditions
• smoking
• low red blood cell levels (pernicious anaemia)
• a family history of stomach cancer
• inheriting a genetic change that causes a bowel disorder such as familial adenomatous polyposis or Lynch syndrome
• chronic inflammation of the stomach (chronic gastritis)
• alcohol consumption
• dietary factors – eating foods preserved by salting and processed meats (e.g. bacon, salami or ham)
• being overweight or obese

About 2100 people are diagnosed with stomach cancer in Australia each year. Men are two times more likely than women to be diagnosed with stomach cancer. It is more common in people over 60, but it can occur at any age. About one in 121 men and one in 290 women are likely to develop stomach cancer before the age of 75.