High Body Fat Level Increases Breast Cancer Risk in Postmenopausal Women with Normal BMI

April 30th, 2019

There is an approximately 30% increased risk of breast cancer recurrence or death in those who are obese, compared to those with ideal body weight. Obesity is associated with alterations in Insulin/glucose homeostasis, adipokines, and sex hormones, which may all play a role in breast cancer outcomes.
BMI (Body Mass Index) does not discriminate between adiposity and muscle, and individuals deemed healthy based on a normal BMI may still be prone to cardiometabolic disorders due to high levels of visceral fat. It has been reported that approximately 18% of women with normal BMI had excess fat, detected on DEXA scan.
In a recently published article in JAMA Oncology involving 3460 postmenopausal women with normal BMI, there was a 56% increase in the risk of developing ER-positive breast cancer per 5-kg increase in trunk fat, despite a normal BMI. This study concluded that a normal BMI may not be an adequate proxy for the risk of breast cancer in postmenopausal women but high body fat levels and altered levels of circulating metabolic and inflammatory factors may be associated with a higher risk of invasive breast cancer.