Exercise Can Protect Girls From Cancer
Posted on: Wednesday, 14 May 2008, 09:10 CDT
New research shows that exercise for females during the teen years may help protect girls from breast cancer later in life. Exercise has always been advised for middle-aged women in order to lower their risk of breast cancer after menopause.
But now, starting young—as young as age 12—may lower the risk even more.
"This really points to the benefit of sustained physical activity from adolescence through the adult years, to get the maximum benefit," said Dr. Graham Colditz of Washington University School of Medicine in St. Louis, the study's lead author.
The researchers tracked 65,000 nurses between the ages of 24 to 42 who enrolled in a major health study. Detailed questionnaires were given to them about their physical activity dating all the way back to age 12. Within six years of enrolling, 550 were diagnosed with breast cancer before menopause. A quarter of breast cancer is diagnosed at younger ages when the cancer is more aggressive.
The research reported in the Journal of the National Cancer Institute showed that physically active women in their teens and young adult years were 23 percent less likely to develop premenopausal breast cancer than women who grew up sedentary.
Regular exercise between ages 12 and 22 made the biggest impact.
"This is not the extreme athlete," Colditz cautioned.
Lower-risk women reported doing 3 hours and 15 minutes of running or other vigorous activity a week. Those who were less athletic reported 13 hours of walking a week. Teens typically reported more strenuous exercise, but walking was most common during adulthood.
Exercise helps women in middle age and beyond by keeping weight down, where after menopause, fat tissue is a chief source of estrogen.
In theory, physical activity itself lowers estrogen levels in younger women. Studies of teen athletes show that very intense exercise can delay onset of menstrual cycles and cause irregular periods.
“The moderate exercise reported in this study was nowhere near enough for those big changes. But it probably was enough to cause slight yet still helpful hormone changes,” said Dr. Alpa Patel, a cancer prevention specialist at the American Cancer Society.
The study examined only premenopausal breast cancer, but Dr. Patel said it is likely and possible that the protection from youthful exercise will last long enough to affect more common postmenopausal breast cancer.
“If you were a bookworm as a teen, it’s not too late,” said Patel. Other research strongly shows the benefits of exercise during the middle-age years in women.
Many breast cancer risks in women can’t be changed, such as how early she starts menstruating, how late menopause hits or family history of the disease.
But Patel stressed that even though the exercise benefit is modest, physical activity and body weight are risk factors that women can control.
Dr. Patel suggests both mother and daughter get off of the couch. "Women who engage in physical activity not only during adolescence but during adulthood lower their risk."
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On the Net:
Washington University School of Medicine
Journal of the National Cancer Institute
Source: redOrbit Staff & Wire Reports
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