Scientists recently found that chronic stress acts as a sort of fertilizer that feeds breast cancer progression, significantly accelerating the spread of disease in animal models.
Researchers at UCLA's Jonsson Comprehensive Cancer Center have discovered that stress is biologically reprogramming the immune cells that are trying to fight the cancer, transforming them instead from soldiers protecting the body against disease into aiders and abettors.
The study found a 30-fold increase in cancer spread throughout the bodies of stressed mice compared to those that were not stressed.
It's long been thought that stress fuels cancer growth in humans. This study provides a model that not only demonstrates that stress can speed up cancer progression, but also details the pathway used to change the biology of immune cells that inadvertently promote the spread of cancer to distant organs, where it is much harder to treat.
"What we showed for the first time is that chronic stress causes cancer cells to escape from the primary tumor and colonize distant organs," said Erica Sloan, a Jonsson Cancer Center scientist, first author of the study and a researcher with the Cousins Center for Psychoneuroimmunology.
"We not only showed that this happens, but we showed how stress talks to the tumor and helps it to spread," Sloan added.
In addition to documenting the effects of stress on cancer metastasis, the researchers were also able to block those effects by treating stressed animals with drugs that block the nervous system's reprogramming of the metastasis-promoting immune cells, called macrophages.
Beta blockers, used in this study to shut down the stress pathways in the mice, are currently being examined in several large breast cancer databases for their role in potential prevention of recurrence and cancer spread, said Dr. Patricia Ganz, director of cancer prevention and control research at UCLA's Jonsson Comprehensive Cancer Center.
If preliminary findings indicate benefit, early phase clinical trials are being considered at the Jonsson Cancer Center testing beta blockers as a means of preventing breast cancer recurrence. Other healthy lifestyle behaviors may also influence the biological pathways described in the study, such as exercise and stress reduction techniques.
"We're going to be focusing on younger women, because they may have a multitude of things weighing on them when they're diagnosed with breast cancer. Younger women have more significant life demands and typically are under more stress," Ganz said.
The study appears in the Sept. 15, 2010 issue of the peer-reviewed journal Cancer Research.