Postmenopausal women who are overweight — and especially obese — have a greater risk of developing breast cancers, finds a new study that highlights the importance of preventing weight gain, as it also raises questions about whether losing weight necessarily reduces that risk.
The study adds to a consistent body of research showing that overweight and obesity increases women’s risk of postmenopausal breast cancers. It was published yesterday in JAMA Oncology.
AICR estimates that a third of US breast cancers could be prevented if women were at a healthy weight throughout life, were active and did not drink alcohol.
In this study, as other research has seen, the heavier the women, the greater the risk. Women categorized as the most obese were at almost double the risk of the most common type of breast cancer, ER-positive, along with PR-positive tumors. These cancers are fueled by the hormones estrogen and progesterone, respectively.
The study used data from approximately 67,000 women who were all part of the Women’s Health Initiative trials. That study focused on preventing certain cancers, heart disease and osteoporosis. When the women entered the study in the mid 1990s they were 50 to 79 years old, and they were weighed. They also answered questions about their lifestyle habits, medical history and other health risk factors. After that, they were weighed annually and had regular mammograms. Continue reading