As little as 15 minutes of physical activity a day can substantially cut death rates in men with prostate cancer, new research hints.

We saw benefits at very attainable levels of activity, lead investigator Dr. Stacey A. Kenfield of Harvard School of Public Health, Boston, noted in a statement from the American Association for Cancer Research Frontiers in Cancer Prevention Research Conference underway in Houston.

She added in an email to Reuters Health, We recommend that men with prostate cancer do some type of physical activity for their overall health, even if it is a small amount, such as 15 minutes of activity per day of walking, jogging, biking, or mild gardening. Vigorous activity may be especially beneficial for prostate cancer, as well as overall health.

The findings stem from 2,686 men with prostate cancer whose physical activity was assessed repeatedly both before and after diagnosis. The subjects were followed between 1986 and 2008.

Regular physical activity -- both vigorous and non-vigorous -- was associated with a lower risk of death from any cause, the researchers found, whereas regular vigorous activity was associated with a lower, but nonsignificant, risk of death due to prostate cancer.

Specifically, men who engaged in physical activities equivalent to jogging, biking, swimming or playing tennis for about a half-hour per week - had a 35 percent lower risk of death from any cause and a modest 22 percent reduction in risk of death from prostate cancer.

Specific to walking, the investigators found that men who walked 4 or more hours per week, compared with those who walked less than 20 minutes per week, had a 23-percent lower risk of death from any cause.

In addition, compared with men who walked less than 90 minutes per week at an easy pace, those who walked 90 or more minutes per week at a normal or very brisk pace had a 51-percent lower risk of death from any cause.

When we looked at prostate-specific mortality, we only saw a benefit with more vigorous activity -- at 5 or more hours of vigorous activity per week, Kenfield told Reuters Health. The percent reduction was 56 percent.

Physical activity, specifically vigorous activity, has been linked with a lower risk of advanced prostate cancer, so we expected to see a protective effect of exercise on death due specifically to prostate cancer, Kenfield commented.

Since physical activity has other well-established benefits including reducing risk of other diseases such as heart disease and diabetes, we expected to see a lower risk for all-cause mortality as well, she added.

While previous studies have focused on how physical activity affects the risk of developing prostate cancer, this is the first large study to examine exercise in relation to death in prostate cancer survivors, Kenfield and colleagues note.