The authors used nude mice that had been inoculated with human ovarian carcinoma cells, and the mice were stressed by being immobilized for several hours a day. Stressed mice had a three-fourfold increase in the number of tumor nodules and tumor weight; they also had more metastases. These results were replicated using other tumor cell lines and another method of stressing the mice.

 The stressed mice had larger adrenal glands and greater sympathetic nervous system activity than the controls, so the authors investigated whether the effect of stress on tumor growth is mediated by -adrenergic receptors. An agonist for 2-adrenergic receptor and a general -adrenergic receptor agonist increased tumor nodule number and tumor weight in a similar manner to chronic stress. Moreover, a -adrenergic antagonist could reverse these effects and the effects of chronic stress itself. By contrast, 1-adrenergic receptor agonists had no effect. [...]

 These results show one way in which stress increases tumor growth  [...]

Source and full text:http://www.nature.com/nrc/journal/v6/n9/full/nrc1986.html

 Original title: Tumorigenesis: Stress and cancer

Author: Patrick Goymer