Researchers found that male asthma sufferers who use inhalers are up to 40 per cent more likely to develop tumours than men without the condition.

Merely having asthma increases a man's likelihood of developing prostate cancer by 26 per cent.

The Australian academics who carried out the study said the results showed the need for more research into the relationship between asthma, inhalers and prostate cancer.

They originally chose to investigate a possible link between the two conditions because both involve an inflammation of the body.

Cancer experts stressed that the new findings - based on an analysis of the medical histories of 1,179 men diagnosed with prostate cancer - were preliminary, and urged asthma sufferers to continue using their inhalers.

Dr Elaine Vickers from Asthma UK told the Daily Mail: "This research suggests their could be a weak association between asthma and prostate cancer risk.

"However even if this is true, the association is marginal, and there is no reason for men with asthma to be concerned."

The study was published in the journal Cancer Epidemiology, Biomarkers and Prevention.