Stomach cancer (also called gastric cancer) is a disease in which malignant cancer cells form in the lining of the stomach.
Stomach cancer can develop in any part of the stomach, a J-shaped organ in the upper abdomen where digestion commences before food passes to the intestines. It is thought to develop slowly over many years.
When muscles in the stomach break down food, gastric juices are released from glands in the mucosa, which is the inner stomach layer. They turn food into a thick fluid and nutrients from this are absorbed through the small bowel’s walls into the bloodstream.
The wall of the stomach is made up of 3 layers of tissue:
- The innermost layer called the mucosal layer.
- The middle layer called the muscularis layer.
- The serosal layer which is the outermost layer.
Around 90 to 95 per cent of stomach cancers develop in cells lining the mucosa – these are called adenocarcinomas, and they spread through the outer layers of the stomach. Other types include squamous cell carcinoma, lymphoma, stromal tumours, and carcinoid tumours, however these are rare.
As stomach cancer often doesn’t cause symptoms until the advanced stages, it is often detected at a later stage. Unusual changes in the stomach lining often preface stomach cancer.