Glossary: tumor

Not normal. An abnormal lesion or growth may be cancer, premalignant (likely to become cancer), or benign (not cancer).

Not cancerous. Benign tumors may grow larger but do not spread to other parts of the body. Also called nonmalignant.

Cancerous. Malignant cells can invade and destroy nearby tissue and spread to other parts of the body.

In medicine, a lump in the body. It may be caused by the abnormal growth of cells, a cyst, hormonal changes, or an immune reaction. A mass may be benign (not cancer) or malignant (cancer).

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Neoplasms may be benign (not cancer), or malignant (cancer). Also called tumor.

A group or layer of cells that work together to perform a specific function.