MedicalResearch: What is the background for this study?
Dr. White: Many studies have shown that being overweight or obese is a risk factor for postmenopausal breast cancer. We know less about how obesity impacts breast cancer risk in premenopausal women.
About a third of U.S. adults are obese, which is defined as having a body mass index (BMI) greater than 30. Similarly, the prevalence of abdominal obesity, measured by a person’s waist circumference, has increased by 10% in the last decade. In 2012, more than two-thirds of U.S. women had a waist circumference that indicated abdominal obesity.
Abdominal obesity may be a better predictor than BMI for breast cancer risk and other chronic diseases, because it is related to insulin resistance and can reflect metabolically active fat stores.
In order to understand how different types of obesity (overall vs. abdominal) influence breast cancer risk, we used information from >50,000 participants in the Sister Study. The Sister Study, led by scientists at the National Institute of Environmental Health Sciences, part of the National Institutes of Health investigates environmental and genetic risk factors for breast cancer.
MedicalResearch: What are the main findings?
Dr. White: We confirmed previous reports that higher BMI is associated with postmenopausal breast cancer risk and found that associations were strongest among women with hormone receptor positive (ER+PR+) tumors. Additionally, we found that waist circumference was an independent risk factor for both premenopausal and postmenopausal breast cancer. After controlling for overall BMI, women who met the definition of abdominal obesity (81-88 cm vs. ≤ 80 cm) had a 16% increase in postmenopausal breast cancer risk, and a 56% increase in premenopausal breast cancer risk.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. White: Abdominal or central obesity, defined by waist circumference, may be a better predictor of breast cancer risk than overall adiposity defined by BMI.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. White: In our study, there were too few premenopausal women to look at ER-/PR- breast cancers specifically. Future research would benefit from having a larger sample size of younger women to better understand the role of body size for hormone receptor negative breast tumors in premenopausal women. As waist circumferences continue to expand in the United States, understanding the long-term health consequences of central adiposity will be critical for addressing breast cancer trends, and other chronic diseases, in the future.
MedicalResearch.com Interview with:, & Dr. Alexandra White PhD in Epidemiology (2015). Abdominal Obesity Raises Risk of Breast Cancer in Pre and Post Menopausal Women MedicalResearch.com