In contrast, men who didn't exercise lost bone mass, says researcher Paula Chiplis, PhD, RN, a clinical instructor and senior research assistant in the department of nursing at Johns Hopkins Hospital in Baltimore.
"With exercise, prostate cancer patients gained bone density at a time in life when even healthy men are starting to lose bone density. This is really exciting," Jennifer Wenzel, PhD, RN, a researcher at Johns Hopkins who also worked on the study, tells WebMD.
The findings were reported at the American Society for Therapeutic Radiology and Oncology's annual meeting.
Men with localized cancer that is confined to the prostate gland can be treated with radiation therapy along with ADT. Radiation is used to kill the cancer cells. ADT inhibits the production of hormones called androgens that feed cancer cells, slowing tumor growth and improving the odds of survival.
Radiation is also thought to weaken bones, although the reasons are less clear, she adds.
Brisk Walking Builds Bones
But exercise can change all that, Chiplis says. In the study, brisk walking led to a 0.49% gain in bone mass in just eight to 10 weeks.
Men who didn't exercise lost 2.21% of their bone mass in the two-month study period; placed in context, healthy men lose between 0.5 to 1% of their bone mass per year, beginning in middle age, she says.
And men undergoing ADT lose 4% to 13% of their bone density annually, Chiplis tells WebMD. "Given these benchmarks, the effect of exercise is huge."
Exercise May Help
The findings grew out of a larger project designed to look at the effects of exercise on fatigue in 70 men with localized prostate cancer undergoing radiation therapy with or without ADT. Half agreed to take brisk 20 to 30 minute walks five days a week during ADT treatment.
Every two weeks, a nurse called all the participants, asking how they were feeling. Those in the exercise group were also urged to hold back or step up their exercises, depending on how they were feeling.
Having a nurse involved probably helped get the men motivated and out of bed, says Phillip M. Devlin, MD, a cancer specialist at Harvard Medical School and a spokesman for ASTRO.
He urges men with prostate cancer to get moving. While the study was small and needs confirmation, "there is no danger in walking and it could possibly be helpful," Devlin tells WebMD.
How fast do you need to walk to reap the benefits? "As briskly as you can and still carry on a conversation," Chiplis says.