CANCER
February 6, 2013

Stress May Derail Prostate Cancer Treatment

Being under stress seems to interfere with the effectiveness of cancer drugs. Beta blockers may help.

Stress is a mind-body experience. Research continues to uncover ways it negatively affects our moods and health, but it can also spur us to our best efforts. Now a study has found that stress lowers the effectiveness of prostate cancer treatments, making it much harder to kill cancer cells and shrink tumors, at least in mice.

Since stress is unavoidable, especially when one is confronted with a cancer diagnosis, the next step is to figure out how to prevent stress from derailing treatment. It appears a common heart drug may help.

Researchers at Wake Forest Baptist Medical Center conducted two separate experiments that tested the effect of stress on prostate cancer in mice. The first used mice that had human prostate cancer cells surgically implanted, causing tumors to grow. The mice were then treated with an experimental cancer drug that's currently in clinical trials. When the mice were kept calm, the drug killed cancer cells and shrank tumors. But when the mice were stressed, the drug was ineffective against cancer cells and did not shrink the tumors.

When the mice were kept calm, the drug killed cancer cells and shrank tumors. But when the mice were stressed, the drug was ineffective against cancer cells and did not shrink the tumors.

The second experiment used mice that were genetically modified to be highly susceptible to prostate cancer. When these mice were repeatedly stressed, the size of their tumors increased. When treated with bicalutamide, a drug currently used to treat prostate cancer in humans, the tumors shrank. But they didn't shrink nearly as much if the mice were subjected to repeated stress.

The effect seems to be due to the increased epinephrine (adrenaline) production that stress causes. Previous studies have suggested that epinephrine protects cancer cells from destruction. The Wake Forest researchers were able to determine the signaling pathway by which epinephrine sets into motion a chain of molecular events that lessens or turns off the process of programmed cell death (apoptosis). With the system turned off, fewer cancer cells die during treatment.

The researchers also found that beta blockers eliminated the effect of stress on tumor growth in the mice in both experiments, presumably by blocking the effects of epinephrine. Beta blockers are heart medicines meant to control blood pressure, slow the heartbeat and treat a variety of other heart conditions. Beta blockers are sometimes used by people to calm their nerves in a pressure situation.

The researchers hope to test whether similar effects occur in the human prostate. If they do, beta blockers may help improve outcomes for some patients undergoing prostate cancer treatment. And other patients may benefit from non-pharmacological ways to lower stress, like meditation.

An article on the study appears in the Journal of Clinical Investigation.

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