Resistant to treatment; occurring in severe form, and frequently fatal; tending to become worse and leading to a course of increasing severity In cancer, malignant tumors are those that are locally invasive and destructive and that can spread to other parts of the body
Cancerous; a growth with a tendency to invade and destroy nearby tissue and spread to other parts of the body SOURCE : http: //cancernet nci nih gov/dictionary html
a term used to describe cancerous tumors which tend to grow rapidly, can invade and destroy nearby normal tissues, and can spread