The influence of psychosocial factors on the immune system (psychoneuroimmunology) and their role for the incidence and progression of cancer

Psychoneuroimmunological research investigates the influence of psychosocia l factors on the immune system. We reviewed clinical studies dealing with t he following three topics: life events, psychological/psychopathological fa ctors and social support, and their influence on cellular and humoral immun e activity. There is strong evidence that stressful life events (especially losses) have a decreasing effect on immunity. Depression has a similar eff ect and may be the mediator between life events and the immune systems. Res ults dealing with the influence of social support on immune functions are s till inconclusive. In the second part, we reviewed prospective studies concerning the role of psychosocial factors on cancer incidence and progression. Most of the life event studies reviewed have methodological problems, thus the results are h eterogeneous. There is some evidence that psychological/psychopathological factors can promote cancer progression. This is even more obvious in case o f insufficient social support.