Can Weight Loss Lower Breast Cancer Risk?

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If having extra body fat increases the risk of postmenopausal breast cancer, can losing weight – by diet, exercise or both –  decrease the risk? It makes sense, but it’s a less well-studied research area. Two recent studies now suggest it can. Both studies focused on indicators or biomarkers of cancer risk.

Today’s issue of Cancer Research Update highlights one of the studies. In that study, researchers looked at how diet, with and without exercise, lowered indicators of inflammation (it did). Chronic inflammation is closely tied to increased risk.

The second study, published last week by the same team of researchers, also teased apart the role of diet and exercise on biomarkers: here it was sex hormones.

The study found that women who lost even five percent of their body weight through diet with and without exercise lowered their levels of circulating estrogen.High levels of estrogen increase risk of postmenopausal breast cancer. The study was published in the Journal of Clinical Oncology.

This study randomly assigned 438 overweight and sedentary 50 to 75 year old women to one of four groups: exercise only, diet only, diet plus aerobic exercise, or no change. After one year, the women who dieted with and without exercise lost an average of 10 percent of their starting weight. Losing just five percent of body weight through diet and/or exercise lowered the levels of several hormones, compared to the controls.

The largest decrease was found for the biologically active form of estrogen called free estradiol. Estradiol decreased 21 percent among the women who only dieted, and 26 percent among those who dieted and exercised. The greater the weight loss, the lower the levels. Testosterone levels also decreased among the women who dieted with and without exercise.

As the authors point out, these biomarkers are only indicators for postmenopausal breast cancer risk. To read more about risk factors for postmenopausal breast cancer, visit here.


    Author: Mya Nelson

    Mya R. Nelson is at American Institute for Cancer Research, where she writes about the research in the field.

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