For breast cancer patients, everyday anxiety and the stress of the disease are inevitable.
But UCLA researchers have found a way to mitigate the effect of stress on the spread of cancer cells in mice with breast cancer.
The solution: Medication that is already used to treat heart disease and hypertension.
According to a study published in September in the journal Cancer Research, metastasis ““ the spread of cancer cells to other organs”“ and the effects of stress is a major factor in mortality rates for breast cancer.
As everyday tensions start to wear on the psyche, neurotransmitters from the sympathetic nervous system are released into the blood stream, where they are circulated, said Dr. Erica Sloan, a Jonsson Comprehensive Cancer Center researcher.
These messenger chemicals then send signals to the immune cells indicating there is chronic stress. The signal is also released locally to areas like the lungs and lymph nodes, areas to which tumor cells migrate, Sloan said.
From there, macrophages, or white blood cells from the immune system, are recruited towards the tumor and the signals from the sympathetic nervous system change the cell environment to one of metastasis, Sloan said.
As a result, researchers found that stress made the breast cancer in mice metastasize 30-fold more quickly, said Dr. Steven Cole, associate professor of hematology-oncology and a Jonsson Cancer Center researcher.
While stress did not increase the size of the initial tumors in the mice, Cole said, it did work as a fertilizer to increase the already existing cancer cells.
But while this suggests that stress contributes to metastasis, Cole emphasized that stress does not cause cancer, which is a common misconception.
To evaluate these claims, researchers incited stress in mice by placing them in a small area from which the mice could not escape. This produced a low-grade stress response similar to daily stress in humans, Cole said.
Sloan emphasized the mice only felt psychological anxiety, as the researchers wanted to look at the effects of the sympathetic nervous system, which generally manages the body’s stress response.
To block metastasis, researchers used beta-blockers, which are drugs that prevent the effect of stress in the body, Sloan said.
When the mice were treated with these drugs, which are also used to treat high blood pressure and anxiety, there was no acceleration of cancer growth. This suggests these drugs could be used in humans as well, since they have few side effects.
“Certainly the idea of targeting the host factor … is a really good idea for treatment,” Sloan said, adding that by targeting the environment in which the tumor cells grow, it could be possible to minimize the spread of breast cancer.
From here, Sloan said she hopes to better understand the role of the macrophages, and why they are recruited to respond to stress.
But for now, she said the results of the study have received positive feedback.
“Women with breast cancer feel that stress is important,” she said. “I think this kind of validates the feeling they have.”