Weight loss after menopause appears to lower the risk of developing invasive breast cancer. Evidence emerges from a large U.S. study published in the journal Cancer, which involved over 60,000 American women. The cause seems to be the increase in hormone levels associated with fat cells. We talked about this issue with Dr. Andrea Sagona, breast surgeon at Humanitas.
Researchers at the City of Hope National Medical Center in Duarte, California, evaluated weight and height to calculate the body mass index (BMI) of more than 61,000 women twice, three years apart. All participants were post-menopausal and among these 3,061 women developed invasive breast cancer. Following patients for an average of 11.4 years, they found that older women who lost weight reduced their risk of developing invasive breast cancer compared to those who were fattening or remaining at the same weight. Compared to women who had a stable weight during the first three years of the study, those who had lost at least 5% of their body weight during those first three years had in fact 12% less chance of developing breast cancer in the following decade.
Overweight as a risk factor
According to the researchers a weight gain of 5% or more is not associated with an increased risk of breast cancer in general. However, even this small percentage of weight gain is associated with a 54% higher risk of developing “triple negative” breast cancer, a type of cancer that is aggressive and difficult to treat.
“Overweight or obese women have an increased risk of postmenopausal breast cancer due to increased hormone levels associated with fat cells – explains Daniel Schauer, of the University of Cincinnati College of Medicine – These hormones, particularly estrogens, can promote the development of postmenopausal breast cancer. Losing weight reduces the levels of circulating hormones. “This is an encouraging result for women – continued the researchers – since a modest but stable weight loss is not an impossible undertaking, while the loss of weight sufficient to return to a category not obese or not overweight is rather difficult to achieve”.