https://www.cbsnews.com/news/walking-seven-hours-a-week-may-lower-breast-cancer-risk/
“Women who stay active after menopause might reduce their risk of breast cancer.New research shows that women who engaged in at least one hour of vigorous physical activity each day significantly lowered their risk for breast cancer compared to those who didn’t exercise. But, even walking at least seven hours per week lowered the risk considerably.The researchers made their determinations based on data on 73,615 postmenopausal women between 50 and 74 years old. The women were all part of the Cancer Prevention Study – II Nutrition Cohort, and enrolled in the study between 1992 and 1993. They were asked to complete a questionnaires about their health and lifestyles at the beginning of the study, and then every two years between 1997 and 2009.

About 9 percent of the women did not exercise, and about 47 percent said that walking was their only physical activity.

The most active women, who had 42 MET hours per week or more (at least one hour of vigorous (3 miles/hr pace) exercise a day), reduced their risk of breast cancer by 25 percent compared to women who were the least active. These women averaged less than 7 MET hours a week, or about two hours of moderately-paced walking.

Looking closely at women who walked as their only form of exercise, researchers saw women who walked seven hours or more per week had a 14 percent lower risk for breast cancer compared to those who walked three hours or less.”  Those who walked even more vigorously than 3 mi/hr pace saw their risk drop by 25%!