Narrator: This is Science Today. About two-thirds of women who get breast cancer after menopause can trace the disease to higher-than-normal levels of estrogen. Previous studies have shown a close link between high levels of estrogen and a higher risk for breast cancer. Dr. Steven Cummings of the University of California at San Francisco is trying to find ways to prevent the onset of estrogen-related breast cancer. Some scientists have recommended a low-fat diet.
Cummings: Unfortunately, most studies have shown no benefit to reducing fat unless you also reduce your weight. Weight loss may reduce your risk so if you reduce the fat level in your diet you may lose weight and that may cause a reduction in your risk of breast cancer.
Narrator: Cummings says women should concentrate on keeping their estrogen levels very low. Since higher estrogen levels are found in heavier women, weight loss is one possibility.
Cummings: So, it can't be explained entirely by the effects of hormones but it's one rational explanation-that by losing weight you might reduce your estrogen level.
Narrator: For Science Today, I'm Larissa Branin.