October 4, 2013
Regular Exercise Significantly Reduces Risk Of Breast Cancer
[ Watch the Video: Walking Away Your Breast Cancer Risks ]
Brett Smith for redOrbit.com - Your Universe OnlineRegular physical activity can benefit women at any age, and a new study from the American Cancer Society has found that active older women are less likely to get breast cancer than women who do not exercise.
Based on a study of almost 74,000 postmenopausal women, ACS researchers found that participants who engaged in an hour of vigorous physical activity every day had a 25 percent lower risk of developing breast cancer. Women who walked for an hour a day on average had a 14 percent lower possibility of breast cancer, according to the team's report in the journal Cancer Epidemiology, Biomarkers, and Prevention.
"We examined whether recreational physical activity, specifically walking, was associated with lower breast cancer risk,” said study author Alpa Patel, senior epidemiologist at the ACS in Atlanta. “Given that more than 60 percent of women report some daily walking, promoting walking as a healthy leisure-time activity could be an effective strategy for increasing physical activity among postmenopausal women.”
“We were pleased to find that without any other recreational activity, just walking an average of one hour per day was associated with lower risk of breast cancer in these women,” Patel added.
Study participants were recruited between 1992 and 1993 for the society’s Cancer Prevention Study-II Nutrition Cohort. The women, all between the ages of 50 and 74 years old, completed surveys on their personal, medical, and environmental information during the enrollment process. Study volunteers also completed follow-up surveys every two years between 1997 and 2009.
The participants also provided data on time spent engaging in various physical activities such as walking, swimming, playing tennis and bicycling. They also reported the number of hours they spent sitting and watching television or reading.
Using participant data, the research team determined the ratio of the energy spent during an activity to resting metabolic rate – referred to as metabolic equivalent (MET) – in total hours for each participant. The scientists found that approximately 9.2 percent of volunteers did not exercise at all and about 47 percent of volunteers reported walking as their only activity. The median MET cost among active women was 9.5 hours per week – the equivalent of 3.5 hours of moderate walking.
"Current guidelines recommend that adults should strive to get at least 2.5 hours per week of moderate-intensity activity, or 75 minutes per week of vigorous-intensity aerobic activity for overall health,” Patel noted. “Higher levels of activity may provide greater benefit for breast cancer prevention.”
The most active women, with about one hour of daily vigorous activity, had a 25 percent lower risk for breast cancer compared with women who were least active, while those who walked for seven hours or more per week had a 14 percent lower risk for breast cancer.
"Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect," Patel concluded. "Our findings are particularly relevant, as people struggle with conflicting information about how much activity they need to stay healthy. Without any other recreational physical activities, walking on average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more."