Stomach Cancer

Cancer 101: Cancer Explained

What is 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, squeeze, and break up 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.

What is cancer and how does stomach cancer spread?

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. The types of cells making up the tumor determine how the tumor will behave.

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 cancer 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, through which they can travel to all the tissues of the body. This process is called metastasis. The cancer cells be found in lymph nodes near the stomach. The cancer cells may invade or attach to other tissues and grow to form new tumors called metastases that may damage those tissues.

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