Cancer is a group of many related diseases. All cancers begin in cells
, the body's basic unit of life. Cells make up tissues, and 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 and die, new cells take their place. Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor
Tumors can be benign or malignant.
Benign tumors are not cancer.
Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer.
They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (primary
) tumor to form new tumors in other organs. The spread of cancer is called metastasis
Stomach cancer, also called gastric cancer, is much more common in other areas of the world than it is in the United States, particularly Japan. The number of people diagnosed with the disease each year is declining. In 2008, 21,500 new cases of stomach cancer were diagnosed in the United States.
Risk factors for stomach cancer include age, gender, race and diet. Most people who develop stomach cancer are age 72 or older. Men are more likely than women to get stomach cancer, and it is more common in Asians, Pacific Islanders, Hispanics and African Americans than in non-Hispanic white Americans.
Studies suggest that diets high in smoked, salted and pickled foods may increase chances of stomach cancer. The bacteria helicobacter pylori, commonly found in the stomach, can cause infections which may increase risk of stomach cancer.