An abnormal mass of tissue formed by cells growing or dividing more than they should or failing to die when they should.
Tumors can be benign or malignant. Benign tumors do not invade nearby tissues or spread to distant parts of the body, although they can sometimes cause problems because of their size or location. Malignant tumors are cancers and can invade surrounding tissues or spread to other parts of the body.
QUICK FACT
A tumor is not automatically cancer. The term describes an abnormal mass; its biological behavior determines whether it is benign or malignant.
COMMONLY CONFUSED WITH
Cancer: a group of diseases involving abnormal cells with uncontrolled growth and the potential to invade or spread. Not every tumor is cancer.
SEE ALSO