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Cancer is a group of many related diseases that begin in cells, the body’s basic unit of life.
The body is made up of many types of cells. Normally, cells grow and divide to produce more cells only when the body needs them. This orderly process helps keep the body healthy. Sometimes, however, cells keep dividing when new cells are not needed. These extra cells form a mass of tissue, called a growth or tumor.
Tumors can be benign or malignant. Benign tumors are not cancer. They can often be removed and, in most cases, they do not return. Malignant tumors are cancerous, with cells that divide without control or order. They 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. The spreading of cancer from the original site to form new tumors in other organ is called metastasis.
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