PHILADELPHIA Obese women might be able to eliminate their increased risk for postmenopausal breast cancer by taking measures during perimenopause to prevent weight gain and to therapeutically control the metabolic effects of their obesity, according to the results of a preclinical study published in Cancer Research, a journal of the American Association for Cancer Research.
"Obese postmenopausal women have increased risk for breast cancer and poorer clinical outcomes compared with postmenopausal women who are lean," said Paul S. MacLean, Ph.D., associate professor of medicine at the University of Colorado Anschutz Health and Wellness Center in Aurora, Colo. "The reasons for this are not fully understood.
"Unfortunately you cannot do the studies needed to address this issue in humans. So, we merged rat models of obesity, breast cancer and menopause to best mimic the events that link premenopausal obesity to an increased rate of postmenopausal breast cancer."
During menopause, women often gain weight because they consume more food than their body needs. In a previous study, MacLean and colleagues used their rat model to show that weight gain following surgical ovariectomy, which models menopause, helped promote breast tumor development in obese rats.
In this study, they confirmed that obesity and overfeeding after surgical ovariectomy together drove aggressive tumor growth and progression.
One reason was that obese rats were unable to appropriately handle the excess sources of energy, in the form of glucose and dietary fat, which accumulated as a result of overfeeding after surgical ovariectomy. Lean rats stored the excess glucose and dietary fat from overfeeding in liver, fat, muscle and healthy breast tissue, a normal metabolic response to overfeeding. In contrast, the healthy tissues in obese rats failed to increase uptake of glucose and dietary fat, but the breast tumors dramatically increased uptake of g
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American Association for Cancer Research