"Some studies have suggested that more physically active men may have a lower risk of prostate cancer, but the associations have tended to be moderate, not always statistically significant, and sometimes only evident among older subgroups or for substantially high, but not moderate, levels of activity," according to background information in the article. However, many of these studies did not research physical activity in detail.
Edward L. Giovannucci, M.D., Sc.D., from Harvard School of Public Health, Boston, and colleagues used data from the Health Professionals Follow-Up Study to assess the association between physical activity and prostate cancer incidence and progression. The number of cases of incident, advanced, fatal, and high-grade prostate cancer was determined for 47,620 U.S. male health professionals in the study, who were followed up from February 1986 to January 2000. Participants were asked to report the average time per week they took part in the following activities during the past year: walking or hiking outdoors, jogging, running, bicycling, lap swimming, tennis, squash or racquetball, and calisthenics or rowing.
During 14 years of follow-up, 2,892 new cases of prostate cancer were diagnosed, including 482 advanced cases. The researchers observed no association for total prostate cancer in relation to total vigorous and nonvigorous physical activity. A lowered risk of advanced and fatal cases of prostate cancer was found in men 65 years or older who were in the highest category of vigorous physical activity. However, these associations were not observed in younger men.
"In conclusion, men 65 years or older engaging at least three hours of vigorous physical activity weekly had a markedly lower risk (almost 70 percent) of being diagnosed as having high-grade, advanced, or fatal prostate cancer," the authors write. "Although the mechanisms still need to be understood, these findings suggest that vigorous 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."
(Arch Intern Med. 2005; 165: 1005-1010. Available post-embargo at www.archinternmed.com.)
Editor's Note: This study was supported by a research grant from the National Institutes of Health, Bethesda, Md.
For more information, contact the JAMA/Archives Media Relations Department at 312-464-JAMA (5262) or email medirelations@jama-archives.org.
Journal
Archives of Internal Medicine