Central obesity bears risk of breast cancer

Women with central adiposity, regardless of menopausal status, are at risk of developing breast cancer, according to a study.

The study used prospective waist (WC) and hip circumference (HC) data in the Nurses’ Health Studies. These measures, along with waist-to-hip ratio (WHR), were analysed in relation to breast cancer incidence independent of body mass index (BMI).

BMI-adjusted multivariable Cox proportional hazards models revealed that WC and HC were not associated with premenopausal breast cancer risk. On the other hand, WHR conferred a risk increase, such that women in the highest WHR quintile had a 27-percent higher risk compared with those in the lowest quintile (hazard ratio [HR], 1.27, 95 percent confidence interval [CI], 1.04–1.54; p=0.01). This association was particularly evident for oestrogen receptor-negative (ER-)/progesterone receptor-negative (PR-) and basal-like breast cancers.

Premenopausal WC, HC, and WHR showed no association with postmenopausal breast cancer risk, with or without controlling for BMI.

Meanwhile, postmenopausal WC, HC, and WHR were all positively associated with postmenopausal breast cancer. But after adjusting for BMI, the association remained significant for only WC (quintile 5 vs 1: HR, 1.38, 95 percent CI, 1.15–1.64; p=0.002). The estimates were greater among never users of hormone therapy and for ER+/PR+ breast cancers.

The findings suggest that mechanisms other than oestrogen may play a role in the relationship between central adiposity and breast cancer. The risk may then be mitigated by maintaining a healthy WC.