An 18-year-long study has found that even a small amount of physical activity raises the odds of survival for men with prostate cancer. The more activity, the better the odds.

The study tracked the amount of physical exercise engaged in by more than 2,700 men who had been diagnosed with prostate cancer after 1990. Assessments were carried out every two years for 18 years total. Over the course of the study, 548 men died. Only 20% of these deaths were due to prostate cancer; the vast majority of deaths were due to other causes.

The results consistently showed that men who exercised more were less likely to die over the course of the study than men who exercised less. Engaging in vigorous physical activities, such as biking and tennis, conferred the strongest survival benefit.

Vigorous activities included biking, tennis, jogging, running and swimming. Non-vigorous activities included walking and stair climbing. The study researchers compared the amounts of time the men spent engaged in these various physical activities to their odds of survival during the course of the study.

Several comparisons brought out the fact that any exercise at all improved survival and that more exercise was better.

Men who engaged in three hours or more of vigorous activity a week had a 50% lower overall death rate and a 61% lower rate of death from prostate cancer than men who engaged in less than one hour of vigorous exercise a week. But as long as the men engaged in some physical activity, their overall chance of survival improved. Five to ten hours of non-vigorous activity a week meant a 28% decrease in overall death rate compared to exercising less than one hour a week. Going above ten hours lowered the death rate even further.

The most popular activity was walking. Seven hours a week of walking conferred a significant survival benefit when compared to walking 20 minutes or less. That's an hour a day. The benefits of walking varied with the pace: men who walked at a normal pace had a 37% lower risk of death than those who walked at an easy pace. This rose to 48% for those who walked at a brisk or very brisk or very brisk pace.

Walking as little as 90 minutes a week at a normal to very brisk pace meant a 46% lower overall death rate than walking for a shorter time period at an easy pace.

The study also found that only vigorous activity seemed to lower the death rate from prostate cancer itself. But because over 80% of the actual deaths were from causes other than prostate cancer, the effects of non-vigorous exercise certainly can't be discounted.

The researchers conclude that even a small amount of physical activity, such as 15 minutes a day, is beneficial to the survival of prostate cancer patients. Three hours or more of vigorous activity a week may substantially improve survival.

An early release of an article detailing the study was published online by the Journal of Clinical Oncology on January 4, 2011. The article will appear in a future edition of the journal.