Catecholamines can mediate stress-related effects on tumor progression.

Studies have implicated behavior as a factor that can influence several aspects of health and have described the complex bidirectional interactions among the CNS, the endocrine system and the immune system that are involved. There is evidence that psychological factors can affect the incidence and progression of some cancers in humans. The hypothesis that stress could be a cofactor is supported by data obtained from animal models. Catecholamines, norepinephrine in particular, have been shown to directly affect various aspects of tumor development that is separate from the well-characterized effects on the cellular immune response to immunogenic tumors. Studies have shown that norepinephrine can directly affect tumor cell behavior and gene expression, further suggesting another mechanism for stress-related modulation of tumor progression. This line of research further suggests that interventions targeting components of the activated sympathetic-adrenal-medullary axis, or the utilization of β-adrenergic receptor-blocking agents, may represent new strategies for slowing down the progression of malignant disease and improving cancer patients' quality of life.