Stress a trigger for prostate cancer, say scientists
Nerves and stress help to trigger and drive prostate cancer, new research suggests.
Branches of the nervous system that control involuntary functions may play important roles in the disease, scientists have discovered.
The research also points to stress, and the body's response to it, being a possible risk factor for prostate cancer.
In addition, it indicates a potential new treatment pathway involving drugs such as beta-blockers, already used to lower blood pressure.
Previous work has shown that some tumours grow and migrate along nerve fibres. Nerves are commonly found in and around tumours, but their role in cancer development has not been clear.
The new study, conducted both on mice and human tissue samples, focused on the autonomic nervous system which governs "automatic" functions such as heart beat and digestion.
Scientists in the US found that both branches of the autonomic nervous system appear to have important cancer-promoting effects.
One branch, the sympathetic nervous system (SNS), regulates the body's 'flight-or-fight' responses to stress and danger, for instance, by revving up heart rate and constricting blood vessels.
The parasympathetic nervous system (PNS), works in opposition to it, helping the body to relax, "rest and digest".
The SNS fuels early phases of prostate cancer while the PNS becomes involved later.
Stress comes into the picture because the study, published in the journal 'Science', revealed how the SNS promotes tumour growth by generating the neurochemical noradrenaline.
The hormone binds to receptor molecules on tumour cells, triggering a cancer-stimulating biochemical response.
PNS nerve fibres release a different chemical that activates a signalling pathway in the connective tissue surrounding tumour cells, helping the cells to break away and invade other parts of the body.
This may explain recent findings of improved survival in prostate cancer patients on beta-blockers, said the scientists.
"Although further studies will be required to dissect the molecular events linking tumour neurogenesis to cancer progression, our data raises the tantalising possibility that drugs targeting both branches of the autonomic nervous system may be useful therapeutics for prostate cancer," they wrote.