High BMI link to lower pre-menopause breast cancer risk
SCIENTISTS have found evidence to suggest women who have a higher body mass index (BMI) have a lower risk of breast cancer before the menopause.
In particular, researchers at the Institute of Cancer Research, London found that 18 to 24-yearolds in the highest BMI category (classed as obese) were 4.2 times less likely to develop breast can- cer before the menopause than those in the lowest category (classed as underweight).
However, health experts warned that the results should not lead women to consider gaining weight as a way of preventing breast cancer.
Previous evidence shows that, after menopause has taken place, excess body weight increases breast cancer risk and this is when breast cancer most commonly develops and where obe- sity remains a leading lifestyle cause of the disease.
The latest research analysed the data of more than 750,000 women from 19 prospective studies, collecting information on women’s weights at different ages before following the participants for a median of 9.3 years.
Around 55,000 women are diagnosed with breast cancer each year in the UK, with nearly 20% of cases in those aged under 50.
Lead author Dr Minouk Schoemaker, of the Institute of Cancer Research, London, said: “Obesity is linked with a higher risk of breast cancer in older women and is one of the leading causes of cancer worldwide.
“But our study shows the link with breast cancer is more complicated than we thought, and that younger women with higher BMIs are at lower risk of the disease before the menopause.
“After the menopause, obese women have an increased risk of breast cancer, which is likely due to oestrogen hormones produced by fat cells. We now need to find out why this effect seems to be reversed in younger women.”
Baroness Delyth Morgan, chief executive at Breast Cancer Now, which helped fund the research, said: “We must be really clear that weight gain should not be considered an approach to prevent breast cancer.”
The study is published in the journal JAMA Oncology.