Exercising may reduce a man’s risk of developing advanced prostate cancer, a large study from Norway suggests.

In the study, men who were the most active were 36 percent less likely to be diagnosed with advanced prostate cancer than their sedentary peers, while they were 33 percent less likely to die from the disease, Dr. Tom I. L. Nilsen and colleagues from the Norwegian University of Science and Technology in Trondheim report.

However, the men’s level of activity had no effect on their overall prostate cancer risk, possibly because exercise influences the aggressiveness of a cancer, rather than the likelihood of cancer developing in the first place, they note.

Studies of exercise and prostate cancer risk have yielded mixed results, Nilsen and his team write in the International Journal of Cancer. To investigate further, they looked at a group of 29,110 men who were followed for 17 years, during which time 957 developed prostate cancer.

There was no relationship between men’s level of recreational activity and their prostate cancer risk overall, the researchers found. However, the more active the men were, the less likely they were to be diagnosed with advanced prostate cancer, and the less likely they were to die of the disease. Compared to men who were sedentary, those who worked out once weekly were 30 percent less likely to be diagnosed with cancer that had spread beyond the prostate.

Two large US studies had similar results, with no effect of exercise on prostate cancer in general but a lower risk of advanced disease or death from the disease for the most vigorously active men, the researchers note.

SOURCE: International Journal of Cancer, December 15, 2006.