Exercise May Reduce Prostate Cancer Risk in Older Men; Study Supports "Watchful Waiting" for Less-Aggressive Tumors

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THREE NEW STUDIES have shed a bit more light on prostate cancer, which will affect one in six men during their lifetime, and suggest ways men might reduce their risk as well as better evaluate their treatment options.

The most extensive of the studies, published in the Archives of Internal Medicine, looked for links between exercise and reduced risk of prostate cancer among 48,000 men working in health professions. The researchers studied data spanning 14 years, during which time 2,892 of the subjects developed prostate cancer, including 482 advanced cases. Participants were quizzed about how much time they spent doing a variety of physical activities: walking, running, hiking, bicycling, swimming laps, rowing, playing racket sports, doing calisthenics.

Among men age 65 or older, researchers found that those who exercised vigorously at least three hours a week had a 70 percent lower risk of advanced or fatal prostate cancer. No such association between exercise and reduced risk was found among younger men.

Previous studies had suggested a link between exercise and reduced risk of prostate cancer, but the association had been tenuous. The new study's lead author, Edward Giovannucci, MD, ScD, a professor of medicine and nutrition at Harvard University and Brigham and Women's Hospital, notes, "Although the mechanisms are not yet understood, these findings suggest that regular vigorous physical activity could slow the progression of prostate cancer and might be recommended to reduce mortality from prostate cancer, particularly given the many other documented benefits of exercise."

A SECOND NEW STUDY, published in the Journal of the American Medical Association (JAMA), spotlights the long-term difference in outcomes between men with localized, low-grade prostate cancers and those with signs of more aggressive tumors. The sharply varying outcomes, measured in a retrospective study over an average follow-up time of 24 years, suggest equally different treatment strategies.

The University of Connecticut study involved 767 men, ages 55 to 74, who had been diagnosed with cancer between 1971 and 1984. Their cancers had not spread beyond the prostate gland and were being treated either with hormone therapy or "watchful waiting." Of the study group, 228 men died from their cancer, mostly within 15 years of diagnosis.

But the researchers found the deaths were overwhelmingly among men with high-grade tumors (those with a Gleason score--a measure of tumor aggressiveness based on a biopsy--of 8 to 10). A total of 66 percent of men with high-grade tumors died during the study period, compared with just seven percent of men with low-grade prostate cancer (score 2 to 4).

The results reinforce the "watchful waiting" approach of little or no treatment for men with less-aggressive prostate cancer. Such patients may be able to avoid radiation or surgery, either of which can cause incontinence and impotence. The study also points to the importance of treatment, however, for men with more aggressive tumors.

The findings contrast with those from a smaller Swedish study published in JAMA last year, which suggested that low-grade tumors could turn deadly after 15 years. The results might have differed because the Swedish subjects may have had different types of tumors or received subsequent hormone treatment, cautions Peter Gann, MD, ScD, of Northwestern University's Feinberg School of Medicine in an accompanying JAMA editorial. "The key thing patients want to know is, 'Am I out of the woods yet?'" says Dr. Gann, a professor of preventive medicine. "But, as long as the mortality rate isn't zero after a time, that question can't be answered."

The lead author of the new study, Peter Albertsen, MD, MS, chief of urology at the University of Connecticut Health Center, says the Swedish research prompted his own investigation, which concluded that "if you survive 15 years, it is unlikely that the tumor will turn ugly and progress." Dr. Albertsen adds, "For men who have chosen to 'follow' low-grade disease, this study reaffirms that their choice was probably prudent. The vast majority of men with low-grade prostate cancer die of other causes."

Despite the widespread incidence of prostate cancer, only one in 33 men actually dies from the disease.

A THIRD, MUCH SMALLER STUDY, presented at the annual meeting of the American Urological Association, suggests possible benefits from pomegranate juice for men with recurrent prostate cancer. The University of California at Los Angeles researchers conducted a clinical trial of 48 men whose prostate specific antigen (PSA) levels were rising after radiation therapy or surgery for prostate cancer. The men drank eight ounces daily of pomegranate juice, which contains antioxidants as well as phytoestrogens, natural estrogen-like plant compounds.

Researchers compared the average PSA doubling time, a measure of tumor activity, before and after the men began drinking pomegranate juice. Previously, the average had been 15 months; after starting the juice regimen, the doubling time lengthened to 37 months, indicating slower cancer activity. Other testing showed decreased cancer-cell division and proliferation and increased cancer-cell death.

The research was funded by a trust that owns the POM Wonderful pomegranate juice company. Study lead author Allan J. Pantuck, MD, an assistant clinical professor of urology, says that, given the promising results, the UCLA scientists are now following up with a much larger randomized clinical trial.

Did you know…

Regular brisk walking can help temporarily overcome depression, improve the quality and duration of your sleep and even boost mental functioning.

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