There are complex if rather ill-defined relationships between stress and the development of various forms of cancer. This is based on the concept of cancer being an on-going dynamic condition throughout the whole body in which, during the normal process of tissue repair and regeneration, abnormal precancerous cells spontaneously evolve. In the normal state of affairs the body's immune system, which is primarily concerned with our resistance to infection, rapidly scavenges and destroys these abnormal cells. In the same way in which adverse environmental conditions – for example extreme cold – can depress the body's immune system, thereby allowing infections to occur apparently spontaneously, another stress-induced reaction by our immune system can allow premalig-nant cells to ‘get away' and therefore develop separate entities within the body which eventually come to light as one form of cancer or another.
It would be a brave man who could put his hand on his heart and say that the relaxation response can prevent cancer; nevertheless, it does seem highly probable that the development of cancer and chronic stress are in some way closely linked together.