After Menopause, High Body Fat Associated with Doubled Risk of Estrogen+ Breast Cancer Interview with:

Neil M. Iyengar, MD Breast Medicine Service Department of Medicine Memorial Sloan Kettering Cancer Center Evelyn H. Lauder Breast And Imaging Center New York, NY

Dr. Neil Iyengar

Neil M. Iyengar, MD
Breast Medicine Service
Department of Medicine
Memorial Sloan Kettering Cancer Center
Evelyn H. Lauder Breast And Imaging Center
New York, NY What is the background for this study?

Response: Obesity is one of the leading modifiable risk factors for the development of hormone receptor positive breast cancer in postmenopausal women.

Traditionally, physicians use a person’s body mass index (weight in kilograms divided by height in squared meters, kg/m2) to estimate body fat levels. A BMI of 30 or greater is considered to be obese, and this level of BMI increases the risk of at least 13 different cancers.

However, BMI is a crude measure of body fat and can be inaccurate. For example, some normal weight individuals (BMI less than 25) have obesity-related problems like diabetes and high blood pressure. Before our study, it was unknown whether high body fat levels in normal weight women contributes to obesity-related cancers such as breast cancer. What are the main findings?

Response: Our main finding is that high body fat levels in postmeopausal women with normal BMIs is associated with about a doubling in the risk of estrogen receptor positive breast cancer (this is the most common type of breast cancer). This is an important finding because healthcare providers currently use body weight and BMI to estimate a person’s metabolic health and risk of obesity-related diseases. Therefore, many postmenopausal women who appear to be healthy by virtue of a normal BMI, may in fact have a “hidden risk” of breast cancer if they have undiagnosed high boy fat levels. What should readers take away from your report? 

Response: BMI is an inaccurate measure of body fat and therefore an inadequate predictor of breast cancer risk in postmenopausal women. Measuring body fat directly can be done easily and through a number of different methods. DEXA scan is one of the most accurate methods, but there are other readily available methods that can also measure body fat such as bioimpedance testing. What recommendations do you have for future research as a result of this work?

Response: In ongoing studies, we are investigating the biological reasons for the increased risk of estrogen receptor positive breast cancer in normal BMI postmenopausal women with high body fat. Future studies of diet, exercise, and/or medications are needed to determine what steps can be taken to reduce body fat and hopefully decrease the risk of fat-related diseases such as breast cancer.


Iyengar NM, Arthur R, Manson JE, et al. Association of Body Fat and Risk of Breast Cancer in Postmenopausal Women With Normal Body Mass IndexA Secondary Analysis of a Randomized Clinical Trial and Observational Study. JAMA Oncol. Published online December 06, 2018. doi:10.1001/jamaoncol.2018.5327

Dec 6, 2018 @ 7:35 pm 

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