Obesity and Overeating Worsens Breast Cancer in Menopause
Scientists at the University of Colorado have found that obesity and overeating may increase the risk for aggressive breast tumor growth in postmenopausal women. Paul S. MacLean, Ph.D., associate professor of medicine at the University, however, states that although this could not be shown in humans, their study, which involved the use of laboratory rats, mimicked the events that link premenopausal obesity to postmenopausal breast cancer.
The authors report in Cancer Research (a journal of the American Association for Cancer Research) that obese postmenopauseal women have been found to have an increased risk breast cancer and had the tendency to have poorer clinical outcomes compared to postmenopausal women who were lean. They have found in a previous study using a rat model, that weight gain, following surgical removal of the rats’ ovaries to induce menopause, increased breast tumor development in obese rats. However, the mechanisms, which led to these results, have been poorly understood. The new study supported their previous findings and demonstrated that obesity and overeating together could drive aggressive progression of the disease.
They propose that while lean rats stored excess glucose and fat from the diet in their healthy tissues after overeating, obese rats could not increase their uptake of glucose and fat in their healthy tissues. Instead, their breast tumors absorbed the glucose. Another explanation involved differences in the molecular profiles of the tumors of lean and obese rats, which was related to expression of genes with regard to energy use and proliferation, a pattern that may be seen in obese women who have similar tumor types.
Finally, the researchers cite that the use of an antidiabetic drug (metformin) reduced the size of the tumors in obese menopausal rats.
The authors believe that lifestyle modification (diet and exercise) and the use of drugs in the perimenopausal period may help reduce the risk for breast cancer in later life.
American Association for Cancer Research. Obesity and overeating during menopause together promote breast tumor growth and progression. ScienceDaily.