Even Modest Physical Activity Reduces Breast Cancer Risk, Study Shows

Physical activity has been shown to reduce the risk of breast cancer after menopause in many studies, and according to a new  study, the effect is occurs very quickly, even with a modest level of activity, like walking 30 minutes a day.

The study looked at the data of almost 60,000 postmenopausal women followed over an 12-year period to determine whether there was a difference between those who had started exercising fairly recently, and those who hadn’t.  The researchers found that women who had exercised regularly within the previous 4 years had a lower risk of invasive breast cancer than women with lower levels of physical activity. The physical activities included walking, cycling and engaging in other sports, and even physical activity of modest intensity seemed to have a rapid impact on breast cancer risk, and was quite rapidly associated with a decrease in breast cancer risk.

In addition, women who had been exercising regularly 5 to 9 years earlier, but had since become less active had a significantly increased risk of breast cancer compared with those who did not. And, compared with the least active women at both time points, they had no significantly decreased risk of breast cancer, indicating that the protective benefits of exercise are only sustained with continued physical activity.

The study is the first to independently assess the association between breast cancer risk and recreational physical activity both 5 to 9 years earlier and within the previous 4 years.

Previous research has shown that recreational physical activity has protective effects of for postmenopausal breast cancer risk. However, little is known about the optimal frequency, duration and intensity of activity needed to reduce the risk. The present study looked at how rapidly the protective effect of physical activity on breast cancer is observed after regular physical activity is initiated, and for how long it lasts after exercise stops.

The main take away? If you already exercise, it’s important to continue in order to keep the benefit of physical activity in terms of decreased breast cancer risk. And, if you don’t already exercise, starting to get more physical activity can very quickly pay off in terms of decreased breast cancer risk. It is not necessary to engage in vigorous or very frequent activities: even walking 30 minutes per day is beneficial.

Further studies are needed to determine what features or types of physical activity are most important in achieving these benefits, and what is the mechanism underlying these effects.