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Breast cancer

22 May 2012

Dieting may lower breast cancer risk

New research suggests that weight loss through exercise and dieting helps overweight women lower the levels of certain hormones in their blood, potentially raising the odds that they'll avoid developing breast cancer.

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New research suggests that weight loss through exercise and dieting helps overweight women lower the levels of certain hormones in their blood, potentially raising the odds that they'll avoid developing breast cancer.

The findings don't prove that losing weight this way will prevent breast cancer. Still, women who take medications to prevent the disease "need long-term solutions for managing their risk," study co-author Dr Anne McTiernan, director of the Prevention Center at the Fred Hutchinson Cancer Research Center, said in a news release from the center.

"Weight loss represents an additional option for long-term breast cancer risk reduction without significant or bothersome side effects," McTiernan added. The study is published in the Journal of Clinical Oncology.

Weight loss and breast cancer

Previous research at the center has suggested that "losing just 5% or more of one's weight could cut by a quarter to a half the risk for the most common, oestrogen-sensitive breast cancers," McTiernan said.

In the new study, researchers wanted to understand how weight loss through exercise, diet or both would affect potentially dangerous levels of hormones in the body.

The investigators randomly assigned 439 overweight-to-obese women to one of four groups. One group exercised (mainly through walking), one group dieted, one group did both and the remaining group did neither. The women were aged 50 to 75 with an average age of 58.

Those who dieted or dieted and exercised lost an average of about 10% of their weight. In addition, they lowered the levels of several hormones.

"The amount of weight lost was key to changes in hormone levels," McTiernan said. "The biggest effect was through diet plus exercise; exercise by itself didn't produce much of a change in weight or oestrogen."

Hormones and breast cancer link

Dr Robert Hiatt, professor and chair of the department of epidemiology and biostatistics at the University of California, San Francisco, cautioned that weight loss has been connected to breast cancer risk after menopause only. "In this stage of a woman's life, most of the circulating oestrogens are no longer coming from the ovaries, which cease to function, but from fat tissue that is capable of producing the same types of oestrogens," said Hiatt, who's familiar with the study findings.

He cautioned that "the study does not say that losing weight lowers the risk of breast cancer. It would take a larger and longer study to prove that. It does, however, suggest than weight loss has the right kind of effect on circulating oestrogens, and it would be reasonable to expect that breast cancer rates would subsequently fall in such women."

Read more:
Warning signs of breast cancer

More information

For more on breast cancer, visit the U.S. National Library of Medicine.


(Copyright © 2012 HealthDay. All rights reserved.)

 

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Breast cancer expert

Dr Gudgeon qualified in Birmingham, England, in 1968. She has more than 40 years experience in oncology, and in 1994 she founded her practice, Cape Breast Care, where she treats benign and malignant breast cancers. Dr Boeddinghaus obtained her qualification at UCT Medical School in 1994 and her MRCP in London in 1998. She has worked extensively in the field of oncology and has a special interest in the hormonal management of breast cancer. She now works with Dr Gudgeon at Cape Breast Care. Read more.

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