Study of postmenopausal women suggested hormone levels mattered more than excess weight
WebMD News from HealthDay
By Kathleen Doheny
HealthDay Reporter
THURSDAY, Jan. 15, 2014 (HealthDay News) -- After menopause, unhealthy insulin levels may predict breast cancer risk even more than excess weight, new research suggests.
The new findings suggest "that it is metabolic health, and not overweight per se, that is associated with increased risk of breast cancer in postmenopausal women," said study co-author Marc Gunter. He is an associate professor of cancer epidemiology and prevention at Imperial College London School of Public Health in England.
While high insulin levels often occur in overweight or obese women, some very heavy women have normal levels of the hormone, experts say. And some normal-weight females have metabolically unhealthy insulin levels.
The study was published Jan. 15 in the journal Cancer Research.
To assess insulin's role in breast cancer risk, Gunter studied more than 3,300 women without diabetes, 497 of whom developed breast cancer over eight years. He analyzed information on their weight, fasting insulin levels and insulin resistance, in which the body does not respond properly to insulin. Insulin helps the body use digested food for energy. A body's inability to produce insulin or use it properly leads to diabetes.
Overweight for the study was defined as a body mass index (BMI) of 25 or more. BMI is a calculation of body fat based on height and weight.
"The women who are overweight but who do not have metabolic abnormalities [as assessed by insulin resistance] are not at increased risk of breast cancer compared to [normal-weight] women," Gunter said.
"On the other hand, normal-weight women with metabolic abnormalities were at approximately the same elevated risk of breast cancer as overweight women with metabolic abnormalities," he added.
Gunter said this seemingly strong link between insulin and breast cancer is not a reason for women to ignore excess pounds. Being overweight or obese does increase the chances of developing insulin problems, he said.
In his study, high fasting insulin levels doubled the risk of breast cancer, both for overweight and normal-weight women.
In addition, women who were overweight and insulin-resistant had an 84 percent greater risk of breast cancer than overweight women who weren't insulin-resistant, he found.
source : Unhealthy Insulin Levels May Boost Breast Cancer Risk
