Is Body Mass Index Associated With Premenopausal Breast Cancer?
Posted: Monday, August 27, 2018
For premenopausal women, increased body mass index (BMI) seems to be inversely associated with the risk of breast cancer diagnosis before menopause, according to a study published in JAMA Oncology by Minouk J. Schoemaker, PhD, of the Institute of Cancer Research, London, United Kingdom, and colleagues. Although the researchers did not recommend weight gain as a preventive measure, they concluded that “Understanding the biological mechanism underlying this association could have important implications for breast cancer prevention.”
From 1963 through 2013, the multicenter study recruited 758,592 premenopausal women between the ages of 18 and 54; 13,082 of these women developed breast cancer. The women were stratified by age from 18 to 24, 25 to 34, 35 to 44, and 45 to 54.
Weight at ages 18 to 24 was significantly correlated with weight at older ages, particularly for the younger age groups: hazard ratios for breast cancer were lower for women in higher BMI categories, with a risk reduction of 23% per categoric difference (5 kg/m2) for 18- to 24-year-olds and a 12% reduction in risk for 44- to 54-year-olds. Overall, there was a 4.2-fold risk gradient between underweight and overweight at ages 18 to 24 and a 1.9- to 2.5-fold risk gradient between these BMI categories at later ages.
Associations with risk per each BMI category were more significant for in situ than for invasive breast cancer, with hazard ratios of 0.76 and 0.88, respectively. Hormone receptor–positive breast cancer was associated with BMI at all ages, whereas hormone receptor–negative breast cancer was consistently associated with only BMI at ages 18 to 24.
