The Telegraph
Saturday , December 8 , 2012
Since 1st March, 1999
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Exercise, diet can cut breast cancer risk

New Delhi, Dec. 7: Obese women who cut their food consumption and increase exercise just before menopause may reduce their risk of post-menopausal breast cancer, a study on laboratory rats has suggested.

The study by a team of US researchers has shown that obesity and overeating during menopause, simulated in rats by the surgical removal of their ovaries, can drive the aggressive growth and progression of breast tumours.

Paul MacLean and his colleagues at the University of Colorado in the US have also demonstrated that an anti-diabetic drug called metformin appears to reduce the tumour load in obese rats after excision of ovaries. The study’s findings are published today in the journal Cancer Research, published by the American Association of Cancer Research.

Their findings, if valid in humans, suggest that the period before menopause is a “critical window of time for determining breast cancer risk later in life”, MacLean said in a media release issued today by the AACR.

“This means that an obese woman’s risk for post-menopausal breast cancer and poor outcome could be reduced by premenopausal lifestyle modifications such as restricted food consumption and increased exercise,” he said in the media release.

MacLean said the study was aimed at trying to understand the observation that obese post-menopausal women have an increased risk of breast cancer and poor outcome, or response to treatment, compared with lean post-menopausal women. The scientists combined rat models of obesity, breast cancer and menopause to, as MacLean put it, “mimic events that link pre-menopausal obesity to an increase risk of postmenopausal breast cancer”.

Their laboratory studies showed differences in the way that lean rats and obese rats processed glucose and dietary fat after the surgical excision of ovaries. The lean rats stored excess glucose and fat in liver, fat, muscles and health breast tissues. But healthy tissues in obese rats could not absorb the glucose and fat, which were, instead, directed to breast tumours.

The study also found that lean and obese rats with breast tumours had different sets of genes activated — the tumours in obese rats had higher activity of genes involved in energy consumption and cell growth.

In an independent study earlier this year, scientists at the University of California reported in the Journal of Clinical Oncology that metformin appears to reduce the risk of post-menopausal breast cancer in obese women.