Stomach Cancer
The stomach
The stomach is a hollow organ in the upper abdomen, under the ribs.
It's part of the digestive system. Food moves from the mouth through the esophagus to the stomach. In the stomach, the food becomes liquid. Muscles in the stomach wall push the liquid into the small intestine.
The wall of the stomach has five layers:
- Inner layer or lining (mucosa): Juices made by glands in the inner layer help digest food. Most stomach cancers begin in this layer.
- Submucosa: This is the support tissue for the inner layer.
- Muscle layer: Muscles in this layer contract to mix and mash the food.
- Subserosa: This is the support tissue for the outer layer.
- Outer layer (serosa): The outer layer covers the stomach. It holds the stomach in place.
Understanding cancer
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.
Sometimes, this process goes wrong. New cells form when the body does not need
them, and old or damaged cells do not die as they should. The buildup of extra cells
often forms a mass of tissue called a growth, polyp, or tumor.
Tumors in the stomach can be benign (not cancer) or malignant (cancer).
Benign tumors are not as harmful as malignant tumors:
- Benign tumors:
- are rarely a threat to life
- can be removed and usually don't
grow back
- don't invade the tissues around them
- don't spread to other parts of
the body
- Malignant tumors:
- may be a threat to life
- often can be removed but
sometimes grow back
- can invade and damage nearby organs and tissues
- can spread
to other parts of the body
Stomach cancer usually begins in cells in the inner
layer of the stomach. Over time, the cancer may invade more deeply into the
stomach wall. A stomach tumor can grow through the stomach's outer layer into
nearby organs, such as the liver, pancreas, esophagus, or intestine.
Stomach cancer cells can spread by breaking away from the original tumor.
They enter blood vessels or lymph vessels, which branch into all the tissues of
the body. The cancer cells may be found in lymph nodes near the stomach. The
cancer cells may attach to other tissues and grow to form new tumors that may
damage those tissues.
The spread of cancer is called metastasis. See the Staging section for
information about stomach cancer that has spread.
Next: What are risk factors and causes of stomach cancer? »
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