Stress can hasten the spread of breast cancer to the bones, research in the online journal Public Library of Science Biology has suggested.
Studies of mice showed that responses to stress made it easier for tumours to take root in the bone.
By dampening down part of the body's "fight or flight" mechanism, scientists were able to prevent the cancer invasion.
The findings raise the possibility of common drugs called beta-blockers being used to prevent the potentially lethal migration of breast cancer to the bone.
Beta-blockers are normally used to treat angina chest pains, irregular heart beat, and high blood pressure.
Dr Florent Elefteriou, director of the Centre for Bone Biology at Vanderbilt University in the United States, said: "If something as simple as a beta blocker could prevent cancer metastasis to bone, this would impact the treatment of millions of patients worldwide."
Previous research had shown that the sympathetic nervous system, which plays a key role in the "fight-or-flight" response to stress, can stimulate bone remodelling.
It also employed some of the same signalling molecules implicated in breast cancer bone metastasis.
"We came to the hypothesis that sympathetic activation might remodel the bone environment and make it more favourable for cancer cells to metastasise there," said Dr Elefteriou.
Clinical evidence showed that breast cancer patients suffering from stress or depression after their initial treatment had shorter survival times.