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International study reveals women with sustained weight loss have reduced risk of breast cancer

Wednesday 18 December, 2019

Sustained weight loss, even small amounts, can lower women’s breast cancer risk, a new study has today revealed.

The study, published today in the Journal of the National Cancer Institute, combined data from ten international cohort studies. Weight was assessed three times over approximately ten years for more than 180,000 women involved in the study.

The results showed women with sustained weight loss had a lower risk of breast cancer than women whose weight remained stable, and the larger the amount of sustained weight loss, the lower the risk of breast cancer. Women who lost 2 to 4.5 kg had an estimated 13 per cent lower risk than women with stable weight. Women who lost between 4.5 and 9 kg had a 16 per cent lower risk. Women who lost 9 kg or more had an estimated 26 per cent lower risk.

Study co-author Professor Roger Milne, Head of Cancer Council Victoria’s Cancer Epidemiology Division, said although high body mass index (BMI) is an established risk factor for breast cancer, until now there has been very little evidence that weight loss could reduce risk.

“Breast cancer is the most commonly diagnosed cancer in women and while we know that excess body weight increases a person’s risk of at least 13 types of cancer, including breast, our study shows that losing weight can reduce a woman’s risk.”

Cancer Council Victoria’s Head of Prevention, Mr Craig Sinclair, said this research was incredibly important information for public-health and it may motivate some people who are overweight to lose weight.

“We know that one third of cancers can be prevented by living a healthy lifestyle. Today two-thirds of Victorian adults are overweight or obese and therefore this research serves as a timely reminder for Victorians to maintain a healthy weight throughout adulthood and to try and avoid weight creeping up as we get older.”

The study was led by investigators from the American Cancer Society and the Harvard T.H. Chan School of Public Health.