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Exercise Lowers Breast Cancer Risk

Moderate Activity Level Cuts Risk of Aggressive Cancer Type by a Third in Older Women

The Impact of Estrogen

Obesity is a source of estrogen in postmenopausal women, and estrogen also drives the development of estrogen-receptor-sensitive tumors.

Since the impact of exercise was strongly linked to body weight for ER+/PR+ tumors, but not for ER+/PR- tumors, the researchers suggest that some other mechanism may be involved in the development of tumors.

"This finding argues against estrogen being the major player for this tumor subtype," Cerhan says.

But from a public health standpoint, the message is the same.

Postmenopausal women can lower their overall breast cancer risk by engaging in regular exercise, says breast cancer researcher Anne McTiernan, MD, PhD, of Seattle's Fred Hutchinson Cancer Research Center.

McTiernan wrote the book Breast Fitness: An Optimal Exercise and Health Plan for Reducing Your Risk of Breast Cancer.

"Lack of exercise and obesity are thought to account for about a quarter of breast cancer cases," she tells WebMD.

"It is clear that women are not as physically active as they should be. We have an epidemic of obesity," she points out.

"Exercising and avoiding weight gain are two important things that women can do to lower their risk," says McTiernan.



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