Bigger women may have smaller breast cancer risk

Study finds a high BMI lowers the risk prior to menopause

Women who are overweight or obese in early adulthood may be inadvertently reducing their risk of developing breast cancer later on, according to a study of 750,000 women.

A team of international researchers including Australians report that for women aged 18-54 with a high BMI, premenopausal breast cancer risk tends to decrease as BMI increases. 

And this link is strongest for women aged 18-24. 

“The inverse association was strongest for hormone receptor–positive breast cancer and was evident across the entire distribution of BMI,” write the researchers in JAMA.

This implies a hormonal mechanism, they say.

“The results of our study suggest that increased BMI is inversely associated with the risk of breast cancer diagnosis before menopause, to a greater magnitude than suggested in previous analyses, and with the strongest associations for BMI at young ages,” the researchers