Women in the study who ate the recommended five servings or more a day of vegetables and fruits and exercised moderately cut their risk of death in half, according to the study authors.
The benefits were seen both in obese and normal-weight women.
Moderate exercise was defined as the equivalent of taking a brisk, 30-minute walk a day, six days a week.
“Even in the women who were overweight, the combination of a fruit and vegetable-based diet and exercise lowered their risk of dying from breast cancer by 50%,” researcher John Pierce, PhD, tells WebMD.
Combination Was Key
Studies examining the impact of diet or exercise on breast cancer survival have been mixed, with some suggesting a benefit and others finding little evidence of an association.
Three to five hours of moderate exercise a week were was associated with a 50% reduction in the risk of dying from breast cancer in a study from Harvard Medical School, reported in 2005.
None of the women were told what to eat or how much to exercise, but they all were interviewed about their diets and physical activity levels when they entered the study between 1991 and 2000.
They were then followed for an average of 6.7 years.
About half as many obese women as lower-weight women reported eating five or more servings a day of fruits and vegetables and exercising regularly (16% vs. 30%).
But regardless of weight, women who ate the healthiest diets and exercised the most had roughly half as many breast cancer-related deaths during the follow-up period as the rest of the study population, including women who ate healthy diets but did not exercise regularly and women who exercised but didn’t eat five or more servings of fruits and vegetables a day.
The study appears in the June 10 issue of the Journal of Clinical Oncology.
Spotlight on Lifestyle
While a 50% risk reduction sounds impressive, American Cancer Society spokeswoman Debbie Saslow, PhD, points out a woman’s risk of dying from early-stage breast cancer is already very low.
The estimated 10-year mortality rate for the women in the trial who combined regular exercise with healthy diet was 7%, compared with roughly twice that for the rest of the study population.
She adds that the study joins a growing body of research suggesting that lifestyle plays an important role in breast cancer.
While there remain many unanswered questions about the impact of diet and exercise on breast cancer, Saslow says breast cancer survivors and women worried about getting the disease shouldn’t wait to adopt a healthy lifestyle.
“Whether a woman has had breast cancer or not, she should be exercising and eating right,” Saslow says.
Pierce and colleagues hope to follow up the study with an intervention trial designed to directly measure the impact of diet and exercise on breast cancer mortality.
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