Stomach cancer develops when cells in any part of the stomach grow and divide in an abnormal way. Tumours can begin anywhere in the stomach, although most start in the stomach’s inner layer (mucosa). This type of cancer is called adenocarcinoma of the stomach (also known as gastric cancer).
If it is not found and treated early, stomach cancer can spread to nearby lymph nodes or to other parts of the body, such as the liver and lungs. It may also spread to the lining of the wall of the abdomen (peritoneum). Rarely, it can grow through the stomach wall into nearby organs such as the pancreas and bowel.
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Who gets stomach cancer?
About 2400 people are diagnosed with stomach cancer in Australia each year. Men are twice as likely as women to be diagnosed with stomach cancer. It is more common in people over 60, but it can occur at any age.
Rare types of stomach cancer
Some less common types of cancer can start in the stomach. These include small cell carcinomas, lymphomas, neuroendocrine tumours and gastrointestinal stromal tumours.
These types of cancer aren’t discussed here and treatment may be different. For more information, call Cancer Council 13 11 20.
Some cancers start at the point where the stomach meets the oesophagus (called the gastro-oesophageal junction). Depending on the type of gastro-oesophageal cancer, it may be treated similarly to stomach cancer or oesophageal cancer.
What causes stomach cancer?
The exact causes of stomach cancer are not known. Research shows that the factors listed below may increase your risk. Having one or more of these risk factors does not mean you will develop cancer. Some people have these risk factors and do not develop stomach cancer.
Some of the risk factors that may lead to stomach cancer include:
- older age
- infection with the bacteria Helicobacter pylori (H. pylori)
- treating non-cancerous conditions with a subtotal gastrectomy
- smoking tobacco
- low red blood cell levels related to pernicious anaemia
- a family history of stomach cancer
- having an inherited genetic condition like familial adenomatous polyposis (FAP), Lynch syndrome, hereditary diffuse gastric cancer (HDGC), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS)
- chronic inflammation of the stomach (chronic gastritis)
- being overweight or obese
- drinking alcohol
- eating foods preserved by salting.
The stomach
The stomach is 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 stomach is a hollow, muscular sac-like organ. The top part of the stomach joins to the end of the oesophagus (the food pipe) and the other end joins to the beginning of the small bowel.
Anatomy of the stomach
What the stomach does
The stomach stores food and breaks it down (digests it). Juices and muscle contractions in the stomach 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 moves into the large bowel, where fluids are absorbed into the body and the leftover matter is turned into solid waste (known as faeces, stools or poo).
Layer |
In the stomach wall |
| 1. mucosa (moist innermost layer) |
|
| 2. submucosa (supports the mucosa) |
|
| 3. muscle layer |
|
| 4. outer layer |
|
→ READ MORE: Stomach cancer symptoms
Key resource
Download a PDF booklet on this topic.
More resources
Dr Spiro Raftopoulos, Gastroenterologist, Sir Charles Gairdner Hospital, WA; Peter Blyth, Consumer; Jeff Bull, Upper Gastrointestinal Cancer Nurse Consultant, Cancer Services, Southern Adelaide Local Health Network, SA; Mick Daws, Consumer; Dr Steven Leibman, Upper Gastrointestinal Surgeon, Royal North Shore Hospital, NSW; Prof Michael Michael, Medical Oncologist, Lower and Upper Gastrointestinal Oncology Service, and Co-Chair Neuroendocrine Unit, Peter MacCallum Cancer Centre, VIC; Dr Andrew Oar, Radiation Oncologist, Icon Cancer Centre, Gold Coast University Hospital, QLD; Rose Rocca, Senior Clinical Dietitian: Upper Gastrointestinal, Nutrition and Speech Pathology Department, Peter MacCallum Cancer Centre, VIC; Letchemi Valautha, Consumer; Lesley Woods, 13 11 20 Consultant, Cancer Council WA.
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