[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 psychosocial factors on the immune systems. We reviewed clinical studies dealing with the following three topics: life events, psychological/psychopathological factors and social support, and their influence on cellular and humoral immune activity. There is strong evidence that stressful life events (especially losses) have a decreasing effect on immunity. Depression has a similar effect and may be the mediator between life events and the immune systems. Results dealing with the influence of social support on immune functions are still 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 heterogenous. There is some evidence that psychological/psychopathological factors can promote cancer progression. This is even more obvious in case of insufficient social support.