In a study (published in Cancer Research, September 2010), investigators from UCLA demonstrated the biological effects of chronic stress leading to a 30-fold increase in the rate of breast cancer metastases in a mouse study. This study adds the the mounting evidence suggesting that the physiologic changes that occur as a result of chronic stress (i.e. increased stimulation of the sympathetic “fight or flight” nervous system) can increase the risk of cancer progression.
The authors examined the effects of chronic stress in mice injected with breast cancer cells. The mice were subjected to a chronic stress model by being confined to a small cage for 2-hours each day for 20-days. During this time, they underwent injection of fluorescent-labeled breast cancer cells and then observed for metastatic spread. They compared the results to a control group of mice that were not subjected to chronic stress. The results were significantly different. The stressed mice had a 30-fold increase in the development of metastases compared to the non-stressed mice. The authors found, in the stressed mice, that cells in their immune system (i.e. macrophages) were genetically altered by the activity of stress hormones in such a way that increased the ability of the injected cancer cells to gain access to the blood system and thereby spread around the body.
Interestingly, the researchers also tested the effects of a stress hormone blocking medication (“beta-blocker”, propranolol) on the stressed mice. What they found was incredible…propronalol completely blocked the effects of stress hormones on causing the rapid progression of cancer metastases! As propranolol is an inexpensive and widely available blood pressure medication, the authors have suggested that it may have a future role in helping to reduce the risk of cancer progression. Furthermore, stress-reduction lifestyle modifications may lead to similar reductions in cancer progression. As an integrative oncologist, I spend much of my time counseling patients on the potential value of stress reduction activities. Numerous studies have demonstrated the physiological changes that occur with stress reduction (i.e. decreased levels of stress hormones, increased immune system activity, decreased inflammation, decreased production of free radical, etc.) Stress has never been proven to be a causal factor in the development of cancer, but it seems increasingly possible that it may lead to biological effects that increase cancer progression and possibly cancer recurrence.
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