Stress does not cause Cancer

Further to the point that something not existing in physical space can not move a physical body I read today that recent research has indicated that the idea that job stress can cause cancer is untrue. As yet it is unclear whether a bereavement can increase the incidence of common cancers. A few years ago I ended up in a bit of a heated debate over whether being 'positive' helped cancer sufferers. Of course being happy is preferable in any situation but I know of no way that the mind can move matter. It is so deeply ingrained in our culture to believe our mental states can control matter that most will disagree with this. There is of course the reverse truth, that physical illness makes you unhappy. Probably down to clumsy and late diagnosis it may appear that the stress caused cancer but isn't it far more likely that due to physiological changes at the early stages of cancer, stress results. There are studies that show that smiling is not only the result of being happy bur smiling can lead to happiness. Here, however, I advance the idea that happiness itself is physiological in nature. Maybe here I cone full circle. Stress is physiological just as all mental states are the result of physical chemical changes in the brain. Could these physical changes of tiny brain matter lead to cancerous growth elsewhere?