The stomach is a storage organ for food. When you eat your meals, food stays in the stomach for a while, and this is where digestion starts. Food is mixed with acid until it is partly liquefied, at which point it is passed into the rest of the bowel for further digestion and for the nutrient absorption.
The stomach is actually a large, hollow muscle, whose movement is controlled by nerves and hormones, triggered by the sight, smell, or sound of food.
How common is stomach cancer?
The incidence of stomach cancer has decreased rapidly over the last 50 years, probably due in part toimproved diet and living conditions. There were 21,000 new cases of stomach cancer reported in the U.S. in 2010 and 10,570 deaths. Stomach cancer is much more common in older people, but sometimes affects patients in their 30s or 40s.
What causes stomach cancer?
Cancers of the stomach are not all the same, and it is likely that there are different causes. Certain conditions of the stomach may predispose to stomach cancer. These include pernicious anemia, chronic inflammation, ulcers, and large polyps.Smoking, and a high salt or high nitrate/nitrite diet may also cause problems. Nitrites are found in cured meats, pickled fish, and may also originate in fertilizers used on food crops. Helicobacter pylori is a bacterium that can infect the stomach and is tied to the development of several types of ulcers and, in turn, stomach cancer. Stomach cancer does not seem to be hereditary.
How does an ulcer turn into a cancer?
The genes that control the growth of stomach cells become disorganized, making the cells grow quickly and beyond their normal boundaries, creating a tumor.
As the tumor enlarges, the cells grow through the lining of the stomach, and can invade adjacent structures, such as fat or the pancreas. Some cells can break away, travel up the bloodstream and go to other sites, such as the liver or lungs. These are known as secondary cancers, or metastatic.