Friday, September 24, 2010

Rigorous exercise can sabotage cancer therapy

'Sabotage': Rigorous exercise one or two days before having chemotherapy or radiation could undermine the treatment (file picture)

Rigorous exercise before cancer therapy 'highly risky' and can sabotage treatment

By Jenny Hope
Last updated at 8:54 AM on 22nd September 2010

Rigorous exercise can sabotage cancer therapy, a new study has found.

Psychological or physical stress one or two days before having chemotherapy or radiation could undermine the treatment.

Scientists found that cancer cells are more likely to resist treatment because the body’s stress responses had been primed for survival.

They suggest people about to undergo chemotherapy or radiation treatment should try to relax and avoid intense activity for around 48 hours.
A woman exercising at the gym

Lead researcher Dr Govindasamy Ilangovan, from Ohio State University, said: ‘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 the treatment.’

The research team carried out a series of experiments in the laboratory, but say the findings are a clear indication that a stress-sensitive protein can aid the survival of cancer cells.

The protein called heat shock factor-1 normally helps tissues and cells cope with stress, and previous research shows it enables heart tissue to survive when threatened by toxic agents.

But this led researchers to suspect it may perform the same function when breast cancer cells are threatened with extinction by treatment.


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Experiments show that heat shock factor-1 activated another protein, known as Hsp27, that kept the tumour cells alive even after they were exposed to radiation and chemotherapy.

Hsp27, which helps to block cell death, interacts with a third protein, p21, which allows cells to repair themselves and keep dividing.

‘We are doing something to kill the cell, but cells have their own compensatory action to oppose that,’ said Dr Ilangovan.

One of the known inducers of heat shock factor-1 is exercise, says a report published in the journal Molecular Cancer Research.

When the cells were put under stress, levels of Hsp27 reached their height within 48 hours, suggesting the protein is highly active in the two days following any stressful event that activates heat shock factor-1.

Dr Ilangovan said ‘The process that sets these activities in motion takes a couple of days.

‘It is not proven in a clinical setting but our hypothesis leads us to strongly caution cancer patients about avoiding stress because that stress might trigger recurrence of cancer cell growth.’

He suspects the wide distribution of heat shock factor-1 in the body means the protein could have an impact on many different cancers.

The research points to possible ways of preventing stress making cancer harder to treat.

A ‘gene-silencing’ molecule called siRNA restored the process of programmed cell death that kills cancer, the scientists found.

However, siRNA is not suitable for patients and no drug currently exists that mirrors its effects.

Arlene Wilkie, director of research and policy, Breast Cancer Campaign said ‘This early research should be treated with caution as it has only been tested on cells in a laboratory and not on cancer patients.

‘It is unrealistic that people who are about to undergo cancer treatment will be able to avoid stress. If you have any concerns talk to your doctor or nurse.’

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