This mass of extra tissue, called a growth or tumor, can be benign or malignant . Benign tumors are not cancer. They can usually be removed and, in most cases, they do not come back. Most important, cells from benign tumors do not spread to other parts of the body. Benign tumors are rarely a threat to life.
Malignant tumors are cancer.
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. The spread of cancer is called metastasis. Most cancers are named for the type of cell or the organ in which they begin. For example, a woman who has a cancer tumor in her breast has breast cancer.