Neoplasia Introduction
Neoplasia literally means "new growth”. A neoplasm, as defined by Willis, is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after the cessation of the stimuli, which evoked the change. In common usage a neoplasm is often referred to as a tumour and the study of tumours is called Oncology. The tumours may be benign or malignant. Malignant tumours are collectively referred to as cancers.