Weight Loss, Genetic Changes and Lower Cancer Risk
Women who lose weight by dieting and/or exercising show genetic changes related to lower cancer risk, finds a new study that helps unravel how excess body fat increases cancer risk.
The study, published in Cancer Prevention Research, strengthens the body of research suggesting that losing weight will lower cancer risk.
In the study, researchers analyzed data from 45 post-menopausal women who were part of a larger study on lifestyle changes and breast cancer risk. The women were all overweight or obese at the start. Researchers randomly assigned the women to one of four groups: One group focused on reducing calories; a second group focused on exercise; the third group both dieted and exercised; and the fourth was the comparison group. Women in the comparison group were asked not to change their diet or exercise habits.
At the start of the study and again after six months, the researchers analyzed blood and fat (adipose) tissue samples. At 6 months, the dieters lost 8.8 kilograms (19 pounds), the exercisers lost 2.5 kilograms (6 pounds), and the women who did both lost almost 8 kilograms (17 pounds), the women who kept their same lifestyle habits lost no weight.
When the researchers analyzed fat (adipose) tissue genes implicated in cancer development, they saw numerous gene expression changes among the women who lost weight. Greater weight loss was linked to change in gene expression in three genes, related to steroid-hormone metabolism and IGF signaling, which are hypothesized to link obesity and cancer. To their surprise, the researchers found no association between weight loss and the vast majority of inflammatory genes that have been linked to cancer growth.
Sources: Kristin L. Campbell, Karen E. Foster-Schubert, Karen W. Makar, et al. “Gene expression changes in adipose tissue with diet- and/or exercise-induced weight loss.” Cancer Prev Res Published OnlineFirst January 22, 2013.