Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial

The goal of this study is to examine how a one-year exercise intervention, as compared to a usual sedentary lifestyle, influences specific biologic mechanisms that are hypothesized to be operative in the association between physical activity and breast cancer risk. These biologic mechanisms include sex hormone concentrations (estrone, estradiol and sex-hormone binding globulin); measures of adiposity and obesity; mammographic density; insulin-like growth factors; and insulin resistance. A two-centered, two-armed randomized controlled trial (RCT) of exercise and risk factors for breast cancer will be conducted. Approximately 334 postmenopausal, sedentary women will be recruited to the study. Participants will be randomized to one of two groups: an exercise intervention, or a control group. The intervention group will undertake five weekly exercise sessions of 60 minutes each; three will be facility-based and two will be home-based each week. The Edmonton and Calgary exercise oncology facilities will be working in collaboration, and each will include both the controls and exercise intervention arms of the trial. The exercise intervention will last for 12 months. The control group will be asked not to change their usual level of activity during that time. Baseline assessments will be obtained of serum sex hormones (estrone and estradiol), measures of obesity and adiposity, mammographic density, serum insulin growth factor (IGF)-1, insulin resistance, aerobic capacity, and psychosocial health measures. At the end of the study, all baseline assessments will be repeated and compared between the two groups. This study will specifically address identified gaps in knowledge, in terms of examining the simultaneous effect of physical activity on several biologic mechanisms in a controlled trial setting, building on evidence from the only other randomized controlled trial on this topic. Strengths of the proposal include the multi-centered setting (utilizing facilities in both Calgary and Edmonton), and the collaboration of an experienced multi-disciplinary research team from across North America.