Scientists may have discovered why men who exercise tend to have a better prognosis if they are diagnosed with cancer of the prostate.

Every year in Ireland, over 2,000 men are newly diagnosed with prostate cancer, while 500 die as a result of the disease. Previous studies have found that exercise appears to improve the outcome of those affected, however the exact reason for this has been unclear.

US scientists decided to investigate this further. They looked at 572 men with prostate cancer whose physical activity levels were known prior to their diagnosis.

The study found that men who regularly walked at a fast pace before their diagnosis were much more likely to have regularly shaped blood vessels in their prostate tumours compared with men who walked slowly.

According to the scientists, previous research ‘has shown that men with prostate tumours containing more regularly shaped blood vessels have a more favourable prognosis compared with men with prostate tumours containing mostly irregularly shaped blood vessels'.

"In this study, we found that men who reported walking at a brisk pace had more regularly shaped blood vessels in their prostate tumours compared with men who reported walking at a less brisk pace," they explained.

They said that this suggests some kind of mechanism ‘by which exercise may improve outcomes in men with prostate cancer'.

"Although data from randomised, controlled trials are needed before we can conclude that exercise causes a change in vessel regularity or clinical outcomes in men with prostate cancer, our study supports the growing evidence of the benefits of exercise, such as brisk walking, for men with prostate cancer," the scientists from the University of California in San Francisco said.

They added that it is reasonable to suggest that these same benefits could apply to other types of cancer and this is an area that should be further studied.

Details of these findings were presented at the AACR Prostate Cancer Foundation Conference on Advances in Prostate Cancer Research in San Diego.