THURSDAY, Sept. 23 (HealthDay News) -- Physical or mental stress one or two days before cancer treatment may reduce the effectiveness of the therapy, researchers have found.

In a series of experiments using breast cancer cell cultures, a research team at Ohio State University found that mental and physical stress -- including rigorous exercise -- activates a stress-related protein that can trigger a chain reaction that enables cancer cells to survive cancer treatments.

Specifically, the investigators discovered that the presence of the heat shock factor-1 (HSF-1) protein could impair the process that kills cancer cells even after their DNA was damaged by radiation or chemotherapy, according to the report published in the Sept. 21 online edition of the journal Molecular Cancer Research.

It may be possible to develop drugs that suppress HSF-1 and use these drugs as a supplement to cancer therapy, the study authors suggested in a university news release. In the meantime, patients should try to avoid physical and mental stress in the days before cancer treatment, they recommended.

"One of the known inducers of (HSF-1) is exercise. I am not against exercise, but the timing is critical. It looks like any intense or prolonged physical activity a couple of days before the start of cancer therapy is highly risky, and has potential to reduce the benefits of treatment," lead author Govindasamy Ilangovan, an associate professor of internal medicine, said in the news release.

More information

The U.S. National Cancer Institute has more about cancer and mental stress.