Malignant

A tumour is malignant if it is able to invade tissue other than where it originally grew (the primary site). Malignant tumours may spread (metastasise) to nearby tissues, or via the blood stream to other parts of the body quite distant from the primary site. New tumours can then form at those new sites. Benign tumours are not cancerous: their cells do not spread to other parts of the body.