Your stomach is a hollow, sack-shaped organ that forms part of your digestive system and is located in your upper abdomen under your ribs.
After you chew and swallow food, it passes down your esophagus and into your stomach, which releases gastric juices to liquefy the food for absorption by your body. Once liquefied, the digested food is pushed into the small intestine by muscles in the stomach wall.
Stomach cancer begins when the cells in the stomach wall begin growing abnormally and don't die off. These abnormal cells begin to interfere with the functioning of normal cells.
Stomach Wall Structure
There are five layers of tissue in the stomach wall. As cancer grows deeper into the layers, the outlook (prognosis) for the patient gets worse. Starting from the inside (deepest layer) to the outside, the stomach layers are as follows:
- Mucosa: This innermost layer produces stomach acid and digestive juice. Most stomach cancers start in the mucosa.
- Submucosa: This is the next deepest layer, after the mucosa.
- Muscularis: The muscularis is the layer of stomach muscle that moves and mixes the stomach contents to aid in digestion.
- Outer Two Layers: The subserosa and serosa are the outer layers that act as a wrapping for the stomach.
- Adenocarcinoma: This cancer forms from the cells lining the innermost layer of the stomach, the mucosa. Most stomach cancers are adenocarcinomas.
- Other Stomach Tumors: Other less common stomach tumors include lymphomas, carcinoid tumors and gastrointestinal stromal tumors (GIST).