Psychoneuroimmunology and cancer: Fact or fiction?

There is substantial evidence from both healthy populations as well. as ind ividuals with cancer linking psychological stress with immune downregulatio n. This discussion highlights natural killer (NK) cells, because of the rol e that they may play in malignant disease. In addition, distress or depress ion is also associated with two important processes for carcinogenesis: poo rer repair of damaged DNA, and alterations in apoptosis. Conversely, the po ssibility that psychological interventions may enhance immune function and survival among cancer patients clearly merits further exploration, as does the evidence suggesting that social support may be a key psychological medi ator. These studies and others suggest that psychological or behavioural fa ctors may influence the incidence or progression of cancer through psychoso cial influences on immune function and other physiological pathways. (C) 19 99 Elsevier Science Ltd. All rights reserved.