Alberta Physical Activity and Breast Cancer Prevention Trial: Sex Hormone Changes in a Year-Long Exercise Intervention Among Postmenopausal Women

Abstract

A B S T R A C T PurposeWe examined how an aerobic exercise intervention influenced circulating estradiol, estrone, sex hormone-binding globulin (SHBG), androstenedione, and testosterone levels, which may be involved in the association between physical activity and breast cancer risk. MethodsA two-center, two-arm randomized controlled trial of exercise was conducted in 320 postmenopausal, sedentary women age 50 to 74 years. Participants were randomly assigned to a 1-year aerobic exercise intervention of 225 min/wk (n ϭ 160) or to a control group who maintained their usual level of activity (n ϭ 160). Baseline, 6-month, and 12-month assessments of estrone, estradiol, androstenedione, and testosterone were quantified by radioimmunoassay after extraction, and SHBG was quantified by an immunometric assay. Intent-to-treat analyses were performed using linear mixed models. ResultsBlood data were available on 309 women (96.6%) at 12 months. Women in the intervention group exercised an average of 3.6 d/wk for 178 min/wk. At 12 months, statistically significant reductions in estradiol (treatment effect ratio [TER] ϭ 0.93; 95% CI, 0.88 to 0.98) and free estradiol (TER ϭ 0.91; 95% CI, 0.87 to 0.96) and increases in SHBG (TER ϭ 1.04; 95% CI, 1.02 to 1.07) were observed in the exercise group compared with the control group. No significant differences in estrone, androstenedione, and testosterone levels were observed between exercisers and controls at 12 months. ConclusionThis trial found that previously sedentary postmenopausal women can adhere to a moderate-to vigorous-intensity exercise program that results in changes in estradiol and SHBG concentrations that are consistent with a lower risk for postmenopausal breast cancer.

Inflammatory Marker Changes in a Yearlong Randomized Exercise Intervention Trial among Postmenopausal Women

“…All participants provided signed informed consent. The study design and methods for the ALPHA Trial have been previously described (30). In brief, a 2-centered, 2-armed, yearlong, randomized controlled exercise intervention trial was conducted between 2003 and 2006 in Calgary and Edmonton, Alberta, Canada among 320 postmenopausal healthy women.…”

“…Here, we describe the effect of our intervention on inflammatory biomarkers; namely, circulating CRP, IL-6, and TNF-a, which were secondary outcomes from the trial. The primary outcomes of the trial, endogenous sex hormone (30), and adiposity changes (31), have been previously reported.…”

Physical Activity and Genitourinary Cancer Survivorship

“…Likewise, the SHAPE trial showed that relative to controls, androgen (but not estrogen) levels decreased significantly in exercisers who lost >2% body fat after 4 months of exercise (Monninkhof et al 2009). In the ALPHA trial, estrogen levels decreased significantly more in exercisers than in controls after 12 months, even after adjusting for weight change, whereas androgen levels did not change significantly (Friedenreich et al 2010a). Unlike the first two trials, the ALPHA trial findings for estrogen suggest an independent role for physical activity.…”

“…Three randomized, controlled trials (RCTs) that were specifically designed to examine the etiologic pathways between physical activity and postmenopausal breast cancer risk have been conducted (Friedenreich et al 2010a;McTiernan et al 1999;Monninkhof et al 2007b). These studies have involved supervised, controlled exercise interventions in which several proposed breast cancer biomarkers were measured and compared between the exercise and control groups to assess the impact of exercise on these biomarkers.…”

“…These studies have involved supervised, controlled exercise interventions in which several proposed breast cancer biomarkers were measured and compared between the exercise and control groups to assess the impact of exercise on these biomarkers. The Physical Activity for Total Health (PATH) study (n = 173) and the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) trial (n = 320) administered a moderate-to vigorous-intensity physical activity intervention of approximately 225 min per week over 12 months (Friedenreich et al 2010a;McTiernan et al 1999); the Sex Hormones and Physical Exercise (SHAPE) study prescribed a combined strength and aerobic training program of approximately 150 min per week to 189 sedentary postmenopausal women over 12 months (Monninkhof et al 2007b). The effects of exercise on a variety of proposed biomarkers of risk have been reported, with more published results anticipated in the future.…”