A new study finds that women may significantly reduce their risk for breast cancer by exercising even a little bit, such as walking.
But the study found the greatest gains in risk reductions from those who exercised about 10 hours or more a week.
For the study, researchers at the University of North Carolina at Chapel Hill in the US compared 1,500 women with breast cancer to more than 1,550 women without breast cancer who were part of the ongoing Long Island Breast Cancer Study Project, which examined environmental causes of the disease.
The researchers found that women who exercised during their reproductive years or post-menopause curbed their risks of developing breast cancer. Women who exercised 10 to 19 hours per week (or at least two hours each day for five days) reduced their risk by about 30 percent, but a woman's risk was reduced for all levels of exercise intensity, even light.
"The observation of a reduced risk of breast cancer for women who engaged in exercise after menopause is particularly encouraging given the late age of onset for breast cancer," study author Lauren McCullough, a doctoral candidate at UNC's Gillings School of Public Health, said in a news release.
The results were published in the June 25 issue of the American Cancer Society's journal Cancer. This study follows another published in the journal BMC Cancer that found that active post-menopausal women also have a reduced risk of breast cancer.
Analyzing data from more than 110,000 post-menopausal women over 10 years, researchers found that those who engaged in more than seven hours per week of moderate-to-vigorous exercise over the course of the study were 16 percent less likely to develop the disease than those who were inactive.