In a recent study, men with prosate cancer were less likely to die if they exercised vigorously for 5 hours a week.

RODALE NEWS, EMMAUS, PA—Physicians have long known that regular exercise can dramatically improve some very serious conditions, such as heart disease, high blood pressure, type 2 diabetes, and stroke. But what they're only now discovering—as shown, for instance, in new research regarding exercise and prostate cancer presented this month at the American Association for Cancer Research meeting in Houston—is that some sweat equity can also improve, and dramatically, the outcomes of people with cancer.

THE DETAILS: A team of epidemiologists from the Harvard School of Public Health in Boston looked at 2,600-plus men who were diagnosed with prostate cancer between 1990 and 2002, while they were enrolled in the Health Professionals Follow-up Study. As part of that study, the men answered questions about their rates of physical activity every year, so exercise data was available from before and after their diagnoses. What they found was that men who engaged in five or more hours of vigorous activity a week had a 56 percent lower risk of dying from prostate cancer.

WHAT IT MEANS: Exercise has what doctors call a "protective effect." In this study of men with prostate cancer, the researchers found that after a prostate cancer diagnosis, exercise was linked with a lower risk of death by all causes, whether the exercise was vigorous or not. "But when we looked at mortality specifically from prostate cancer, we only saw a significant benefit with more vigorous activity—at the level of five or more hours of vigorous activity per week," says lead author Stacey Kenfield, Sc.D., a research associate at Harvard School of Public Health. So while any type of exercise is beneficial for overall health, for prostate cancer, it seems more vigorous levels are needed to see a benefit.

Other studies evaluating the link between exercise and survival after the diagnosis of colorectal and breast cancers suggest that exercise also improves the odds of surviving those cancers. It's not clear why or how exercise can have beneficial effects for cancer patients, though. "There are a number of molecular pathways through which exercise could exert an effect on prostate-cancer biology," says Kenfield. "For instance, exercise influences hormones thought to stimulate prostate cancer." Exercise can improve your sleep and your mood. Plus, exercise in general improves immune function and can reduce systemic inflammation—all good stuff for trouncing cancer.