(i) Contact inhibition Normal cells have the property of contact inhibition (stoppage of growth on coming in contact with other cells), but cancer cells do not have this property. As a result, cancer cells divide continuously to give rise to a mass of cells (tumours).Metastasis This property is exhibited by malignant
tumours. It is the pathological process of spreading of cancerous cells to different parts of the body. These cells divide uncontrollably, forming a mass of cells called tumour. From the tumour, some cells get sloughed off and enter the bloodstream. From the bloodstream, these cells reach near by as well as distant parts of the body therefore, initiating the formation of new tumours by dividing actively.
(ii) The biological response modifiers such as a-interferons are given to cancer patients as a part of their treatment because it activates patients’s immune system and helps in destroying the tumour.