Abstract
Epidemiologic studies have reported associations between weight fluctuations and postmenopausal breast cancer risk; however, the biological markers involved in this association are unknown. This study aimed to explore the associations between breast cancer–related biomarkers and weight regain following exercise-induced weight loss.
From the 400 participants included in the Breast Cancer and Exercise Trial in Alberta, a total of 214 lost weight during the intervention and had follow-up blood samples, body composition, and covariate measurements. Outcomes were measured at baseline, 12 months (end of the study), and 24 months (follow-up).
During follow-up, weight regain was 1.80 kg [95% confidence interval (CI): –0.40–3.90], and was significantly associated with increases in estradiol [treatment effect ratio (TER) = 1.03; 95% CI, 1.01–1.04], estrone (TER = 1.02; 95% CI, 1.01–1.03), free estradiol (TER = 1.04; 95% CI, 1.02–1.05), the homeostatic model assessment for insulin resistance (TER = 1.03; 95% CI, 1.02–1.05), and insulin (TER = 1.03; 95% CI, 1.01–1.04), and decreases in sex hormone–binding globulin (SHBG; TER = 0.98; 95% CI, 0.97–0.99) levels. Nonstatistically significant associations were found for glucose and C-reactive protein. Furthermore, a statistically significant linear trend of increasing levels for all biomarkers, and decreasing SHBG, across weight regain categories was found.
These results suggest that weight regain following exercise-induced weight loss is associated with breast cancer–related biomarker changes in postmenopausal women.
These findings provide evidence to support the importance of developing effective strategies to prevent weight regain and, consequently, decrease postmenopausal breast cancer risk via changes in adiposity-related biomarkers.
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