Window of Weight Gain May Affect Breast Cancer Risk
The research is clear that obese, postmenopausal women are at increased risk of developing breast cancer. A recent animal study now may help explain how weight gain during menopause may fuel tumor growth, and why those years moving into menopause may be a pivotal time period for women to avoid weight gain to prevent cancer.
The study was published in last month’s issue of Cancer Research and was partially funded by AICR.
An earlier animal study by the researchers found that weight gain after menopause affected tumor growth. In this study, the researchers investigated the affect of being lean and obese during that period of time. Study researchers used tracers to see where fat and glucose went in rats’ bodies and tumors. The young animals had been fed a high fat diet; some of the animals became obese and others remained lean. The researchers then mimicked menopause in the animals.
The lean animals had a normal response, much like a person they stored the excess calories in the liver, skeleton, and various other places in the body. In the obese animals, the tumors were taking up the excess calories. Tumors from the obese animals also displayed an increased expression of the receptor for the hormone progesterone (PR+). Treatment with the antidiabetic drug metformin caused the animal's tumor growth to decrease and tumors expressed lower levels of progesterone.
The findings suggest the importance for women to maintain a healthy lifestyle, especially during the period of menopausal weight gain, note the authors.
Source: E. D. Giles, E. A. Wellberg, D. P. Astling, S. M. Anderson, A. D. Thor, S. Jindal, A.-C. Tan, P. S. Schedin, P. S. MacLean. Obesity and Overfeeding Affecting Both Tumor and Systemic Metabolism Activates the Progesterone Receptor to Contribute to Postmenopausal Breast Cancer. Cancer Research, 2012; 72 (24): 6490