Men with prostate cancer who exercise may have a lower their risk of dying from the disease than those who don't, according to a new study.

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 to very brisk pace had a 46 percent lower risk of dying from any cause over the 18-year study.

The researchers also found that men who did more vigorous activity had the lowest risk of dying from the disease. It is the first study in men with prostate cancer to evaluate physical activity after diagnosis in relation to prostate cancer-specific mortality and overall mortality, according to a statement from the Harvard School of Public Health.

"Our results suggest that men can reduce their risk of prostate cancer progression after a diagnosis of prostate cancer by adding physical activity to their daily routine," said Stacey Kenfield, lead author of the study and a Harvard School of Public Health researcher. "This is good news for men living with prostate cancer who wonder what lifestyle practices to follow to improve cancer survival."

Prostate cancer is the most frequently diagnosed form of cancer among men in the United States, and affects one in six U.S. men during their lifetime. More than 2 million men in the U.S. and 16 million men worldwide are prostate cancer survivors, the researchers said.

The findings are based on a group of 2,705 men diagnosed with prostate cancer who participated in the Health Professionals Follow-Up Study. The participants reported the average time per week they spent doing physical activity, including walking, running, bicycling, swimming and other sports and outdoor work.

The results showed that both non-vigorous and vigorous activity were beneficial for overall survival.

But only vigorous activitydefined as more than three hours per weekwas associated with reduced prostate cancer mortality. Men who did vigorous activity had a 61 percent lower risk of dying from prostate cancer than men who did less than one hour of vigorous activity per week.

"We observed benefits at very attainable levels of activity, and our results suggest that men with prostate cancer should do some 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 gardening," said Kenfield. "However, doing vigorous activity for three or more hours per week may be especially beneficial for prostate cancer, as well as overall health," she said.

The study was published online on Jan. 4 in the Journal of Clinical Oncology.