A study by Thakar et al, published in the journal Nature Medicine, showed that chronic behavioral stress results in higher levels of tissue catecholamines, greater tumor burden and more invasive growth of ovarian carcinoma cells in a mouse model.

Chronic stress is mediated by epinephrine, which is lymphocytotoxic, and cortisol, which is an immunosuppressant. Studies suggest that prolonged activation of either the sympathetic nervous system and/or the hypothalamic-pituitary adrenal (HPA) axis due to chronic stress may promote tumor growth. Cell culture studies suggest that catecholamine stimulation of cancer cells leads to increased production of vascular endothelial growth factor (VEGF) which mediates new blood vessel formation in tumors promoting their growth and spread. Increasing evidence from mouse models suggests that stress-induced neuroendocrine activation does not affect primary tumors, but does promote metastatic spread (Sloan, 2010; Rozniecki, 2010).