Previous studies have found that obesity is a risk factor for postmenopausal breast cancer. Now a new study suggests that losing weight after the age of 50 may help decrease the risk of breast cancer in postmenopausal women not using postmenopausal hormones by up to 26%.
For their study, the researchers used data from 180,885 women aged 50 or older who participated in the Pooling Project of Prospective Studies of Diet and Cancer. The women were followed for approximately 10 years and weight was assessed at baseline, 5 years, and 10 years. All cases of breast cancer were recorded.
Women who had sustained weight loss had a significantly lower risk of breast cancer compared to women who did not lose weight. Specifically, women who lost between 4.5 and 10 pounds had a 13% lower risk. Women who lost between 10 and 20 pounds had a 16% lower risk, and women who lost 20 pounds or more had a 26% lower risk. Even women who initially lost at least 20 pounds and gained some of it back had a lower risk than women who did not lose any weight.
The study was conducted by researchers from the American Cancer Society, Harvard University, and the University of Minnesota. It was published on December 17, 2019 in the Journal of the National Cancer Institute.