BackgroundExercise has favorable effects on biomarkers associated with a lower risk of breast cancer, however it is unclear if higher doses of exercise provide additional effects. No clinical trial has systematically examined how different exercise volumes influence the mechanisms underlying breast cancer etiology. The Breast Cancer and Exercise Trial in Alberta (BETA) - a follow-up study to the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial - is examining how a one-year, high versus moderate volume aerobic exercise intervention influences several biomechanisms hypothesized to influence breast cancer risk in a group of postmenopausal women. Secondary aims are to compare intervention effects on psychosocial and quality of life outcomes as well as understand exercise adherence at 12 and 24 months, and maintenance of all study outcomes at 24 months.Methods/DesignThe BETA Trial is a two-center, two-armed randomized controlled exercise intervention trial conducted in 400 previously inactive, postmenopausal women aged 50–74 years, in Alberta, Canada. Participants were randomly assigned to a one-year aerobic exercise intervention of either high volume (300 minutes/week) or moderate volume (150 minutes/week). Blood draws and accelerometry were performed at baseline, six and 12 months. Baseline and 12-month measurements were taken of adiposity (including dual energy X-ray absorptiometry and computed tomography scans), physical fitness, dietary intake, self-reported physical activity and sedentary behavior, quality of life, perceived stress, happiness, sleep, and determinants of exercise adherence. Exercise maintenance was assessed and all study measurements were repeated at 24 months. Blood will be analyzed for endogenous estrogens, insulin resistance indicators, and inflammatory markers.DiscussionThe BETA Trial will compare the impact of a high versus moderate volume of aerobic exercise on a variety of biological, physiological, and psychological outcomes of relevance to postmenopausal women. A tightly controlled exercise intervention and objective outcome measurements are methodological strengths. The BETA Trial will inform future prevention initiatives by assessing adherence to a high volume of exercise over 12 months by postmenopausal women, and the ability of these women to maintain activity over the longer-term. The ultimate objective is to inform public health guidelines for reducing breast cancer risk through physical activity.Trial registrationClinical Trials Registration Number: NCT01435005

Exercise dose comparison trials with biomarker outcomes can identify the amount of exercise required to reduce breast cancer risk and also strengthen the causal inference between physical activity and breast cancer. The Breast Cancer and Exercise Trial in Alberta (BETA) tested whether or not greater changes in estradiol (E 2 ), estrone, and sex hormone-binding globulin (SHBG) concentrations can be achieved in postmenopausal women randomized to 12 months of HIGH (300 min/week) vs MODERATE (150 min/week) volumes of aerobic exercise. BETA included 400 inactive postmenopausal women aged 50-74 years with BMI of 22-40 kg/m 2 . Blood was drawn at baseline and 6 and 12 months. Adiposity, physical fitness, diet, and total physical activity were assessed at baseline and 12 months. Intention-to-treat analyses were performed using linear mixed models. At full prescription, women exercised more in the HIGH vs MODERATE group (median min/week (quartiles 1,3): 253 (157 289) vs 137 (111 150); P!0.0001). Twelve-month changes in estrogens and SHBG were !10% on average for both groups. No group differences were found for E 2 , estrone, SHBG or free E 2 changes (treatment effect ratios (95% CI) from linear mixed models: 1.00 (0.96-1.06), 1.02 (0.98-1.05), 0.99 (0.96-1.02), 1.01 (0.95, 1.06), respectively, representing the HIGH:MODERATE ratio of geometric mean biomarker levels over 12 months; nZ382). In per-protocol analyses, borderline significantly greater decreases in total and free E 2 occurred in the HIGH group. Overall, no dose effect was observed for women randomized to 300 vs 150 min/week of moderate to vigorous intensity exercise who actually performed a median of 253 vs 137 min/week. For total and free E2, the lack of differential effect may be due to modest adherence in the higher dose group.

BackgroundTo our knowledge, the Alberta Moving Beyond Breast Cancer (AMBER) Study is the first and only prospective cohort study of breast cancer survivors that includes objectively-measured physical activity (PA), sedentary behavior, health-related fitness (HRF), and biologic mechanisms focused on understanding breast cancer outcomes. The purpose of the present study was to report on the feasibility of recruitment, baseline measurement completion, and the representativeness of the first 500 participants.MethodsAMBER is enrolling newly diagnosed stage I (≥T1c) to IIIc breast cancer survivors in Alberta, Canada. Baseline assessments are completed soon after diagnosis and include cardiorespiratory fitness, musculoskeletal fitness, body composition, objective and self-reported PA and sedentary behavior, lymphedema, and blood collection.ResultsBetween July 2012 and November 2014, AMBER recruited its first 500 participants from a pool of 1,447 (35 %) eligible breast cancer survivors. Baseline HRF assessments were completed on ≥85 % of participants with the exception of upper body strength. Collection of ≥4 days/week of monitoring for the Actigraph GT3X® and ActivPAL® were obtained from 90 % of participants. Completion rates were also high for blood (99 %), lymphedema (98 %), and questionnaires (95 %) including patient-reported outcomes and correlates of exercise. The first 500 participants in AMBER are an average age of 56 years, 60 % are overweight or obese, and 58 % have disease stage II or III.ConclusionDespite the modest recruitment rate and younger age, AMBER has demonstrated that many newly diagnosed breast cancer survivors are willing and able to complete a wide array of sophisticated and physically demanding HRF and PA assessments soon after diagnosis. AMBER is a unique breast cancer survivor cohort that may inform future randomized controlled trials on lifestyle and breast cancer outcomes as well as PA behavior change in breast cancer survivors. Moreover, AMBER may also inform guidelines on PA, sedentary behavior, and HRF for improving breast cancer outcomes and survivorship.

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