Weight loss after menopause linked to lower breast cancer risk

A US study suggests that older women who lose weight may have a lower risk of developing invasive breast cancer than those who maintain or gain weight.

Obesity has long been said to  increased risk of breast cancer, previous research has offered a mixed picture of the potential for weight loss to help reduce that risk. For the current study, researchers assessed weight and height to calculate body mass index (BMI) for more than 61,000 women twice, three years apart.

 

Women who lost at least 5 percent of their body weight during those first three years were 12 percent less likely to develop breast cancer over the next decade or so, compared with women who had stable weight during the initial three years of the study.

“Our results are consistent with a woman being able to lower their cancer risk, even if they remain overweight or obese after losing some weight, since almost none of the women in our current cohort analysis lost sufficient weight to achieve normal weight,” said lead study author Dr. Rowan Chlebowski of the City of Hope National Medical Center in Duarte, California.

“That should be an encouraging result for women since modest sustained weight loss can be achievable by many, while weight loss sufficient to return to a non-obese or overweight category is quite difficult,” Chlebowski said.

All of the women in the study had gone through menopause, when menstruation stops and production of the hormone estrogen drops. After menopause, women’s main source of estrogen is fat tissue; being overweight or obese can increase the risk of cancer because estrogen can help tumors grow.

“Women who are overweight or obese likely have an increased risk of postmenopausal breast cancer due to increased hormone levels associated with fat cells,” said Dr. Daniel Schauer of the University of Cincinnati College of Medicine, who wasn’t involved in the study.

“These hormones, especially estrogen, can promote the development of postmenopausal breast cancer,” Schauer told Reuters Health by email. “Losing weight decreases the levels of circulating hormones.”

 

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