Stomach cancer

Stomach cancer

What is stomach cancer?

Stomach cancer is a malignant tumour found in the tissues of the stomach. The cancer starts in the mucosa and as the tumour grows deeper into the stomach wall the risk that it might spread to other parts of the body increases.

Most stomach cancers start in the lining (mucosa) in the upper part of the stomach. This type of cancer is called adenocarcinoma of the stomach. Stomach cancer is also known as gastric cancer.

If it is not found and treated early, stomach cancer can grow through the stomach wall into nearby organs such as the pancreas and bowel. Stomach cancer can also spread into the lymphatic system to nearby lymph nodes or through the bloodstream to other parts of the body, such as the lungs.

It may also spread to the lining of the abdominal cavity (peritoneum), which can cause swelling in the abdomen.

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The stomach and digestive system

The stomach is part of the upper gastrointestinal (GI) tract and the digestive system.

It 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 stores food that has been swallowed and assists with the absorption of some vitamins and minerals. The stomach also acts to pass the food and water into the rest of the digestive system, including the small and large bowel, where most of the processing of food takes place.

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

  • mucosa it produces fluids that start breaking the food down
  • submucosa supports the mucosa and gives it blood to survive and take away any of the nutrients
  • muscle layer (muscularis) it helps to mash the food up and assists with pushing the food into the digestive system in a controlled way
  • outer layer (serosa) surrounds the layers of the stomach.

How the stomach works

Acidic (gastric) juices are released from glands in the stomach mucosa. These juices break food down into a thick fluid, which then moves into the small bowel. Nutrients from the food are absorbed into the bloodstream.

The waste matter moves into the large bowel (large intestine), where fluids are reabsorbed back into the body and the rest is passed out of the body as a bowel movement.

Digestive system stomach & oesophageal 2015

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What are the risk factors for stomach cancer?

The exact causes of stomach cancers are unknown, but some factors may increase your risk.

Having one or more of these risk factors does not mean you will develop stomach cancer. 

Common risk factors for stomach cancer include:

  • smoking
  • high alcohol consumption
  • a diet low in fresh fruit and vegetables
  • infection with Helicobacter pylori (H. pylori), a type of bacteria found in the stomach
  • low red blood cell levels (pernicious anaemia)
  • chronic inflammation of the stomach (chronic gastritis)
  • a personal or family history of stomach cancer
  • inheriting a genetic change that causes the bowel disorders familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (HNPCC).

See your doctor if you are concerned about your risk factors or any symptoms you are experiencing.

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Who gets stomach cancer?

Each year, around 2000 people in Australia are diagnosed with stomach cancer. Stomach cancer makes up 2% of cancer cases in men and 1.4% of cancer cases in women.

Stomach cancer is more common in men – 70% of people diagnosed with stomach cancer are male.

Around 80% of stomach cancers are diagnosed in people aged 60 years and older. The average age that people are diagnosed with cancer of the stomach is around 71.


This information was last reviewed in November 2015
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