Weight, waistline changes influence future breast cancer risk

Changes in weight and waist circumference appear to have a dose-response association with the risk of future breast cancer, such that the greater the gain, the higher the risk, according to a retrospective study.

The study used data from the population-based Korean National Health Insurance Service (NHI) database. They identified 691,253 premenopausal and 1,519,211 postmenopausal women aged ≥40 years. All of the women consecutively underwent three biennial breast cancer screenings between 2009–2014 and were followed up until 2020.

Researchers calculated the percentage changes in weight and waist circumference during the three screenings. They then grouped the women into five categories based on the magnitude of increase or decrease in weight and waist circumference.

Over a median follow-up of 6.9 years, 9,485 premenopausal and 12,553 postmenopausal women developed breast cancer. The risk of breast cancer was elevated among postmenopausal women with two consecutive weight gains (hazard ratio [HR], 1.11, 95 percent confidence interval [CI], 1.01–1.22). Conversely, consecutive weight loss conferred a protective effect (HR, 0.84, 95 percent CI, 0.76–0.93).

Single-time and continuous reductions in waist circumference were associated with a reduced risk of breast cancer (HR, 0.91, 95 percent CI, 0.85–0.98 and HR, 0.84, 95 percent CI, 0.76–0.93). On the other hand, single-time and continuous increases were associated with a risk increase (HR, 1.08, 95 percent CI, 1.01–1.15 and HR, 1.13, 95 percent CI, 1.04–1.22).

Among premenopausal women, only single weight gain was associated with an increased breast cancer risk (HR, 1.07, 95 percent CI, 1.01–1.13).