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Regular exercise, even at a modest intensity, can impact breast cancer risk, says expert.
Middle-aged women who get a few hours of activity each week, including walking or more vigorous exercise, are less likely to be diagnosed with breast cancer than more sedentary women, according to a new study from France.
“The women who recently, in the previous four years, performed physical activity had a decreased risk of breast cancer compared with women who were not so active,” says co-author Françoise Clavel-Chapelon. But that decrease disappeared after the physical activity stopped, she added.
“We looked at recreational physical activity and even if it’s of modest intensity, had a rapid impact on breast cancer risk,” says Clavel-Chapelon from the Institut Gustave-Roussy in Villejuif, France.
Of the 59,308 postmenopausal women followed between 1993 and 2005 in the study, the women who were most active were less likely to be diagnosed with breast cancer. The women who walked for at least four hours a week or doing more vigorous exercise, like cycling, for at least two hours a week were least likely to be diagnosed with breast cancer, according to the results in the journal Cancer Epidemiology, Biomarkers & Prevention.
That apparent benefit was limited to exercise within the previous four years, the researchers found, and exercise five to nine years in the past had no effect on the risk. High levels of recent physical activity were associated with a 10% decrease in risk for breast cancer.
While the study is observational, meaning no group of women was actually given an exercise prescription, researchers still believe that the correlation is present. There have been over a hundred other studies on physical activity and breast cancer risk with similar results. Also, staying active means reducing body fat and that contributes to decreasing the risk factor.
“We actually conducted a study in 2001, a population-based case-control study measuring lifetime physical activity,” says Christine Friedenreich, who was not involved in this study. Activity levels after menopause, whether or not the woman had been active earlier in her life, were most important in predicting breast cancer risk, she says.
Friedenreich, of the department of Cancer Epidemiology and Prevention Research of Cancer Control Alberta in Calgary adds that when a woman went from sedentary to active after menopause, her breast cancer risk decreased by 40%. One who had exercised regularly for life decreased her risk by 42% compared to a non-exerciser, Friedenreich says.
“It’s never too late to start being physically active even if you have never been physically active before,” she adds.
Spending more time per week on less intense activity seemed to offer the same benefit as shorter periods of more intense activity, Clavel-Chapelon noted, but Friedenreich still favours more vigorous activity.