Dose-response effects of aerobic exercise on estrogen among women at high risk for breast cancer: a randomized controlled trial.

UNLABELLED: Medical and surgical interventions for elevated breast cancer risk (e.g., BRCA1/2 mutation, family history) focus on reducing estrogen exposure. Women at elevated risk may be interested in less aggressive approaches to risk reduction. For example, exercise might reduce estrogen, yet has fewer serious side effects and less negative impact than surgery or hormonal medications. Randomized controlled trial. Increased risk defined by risk prediction models or BRCA mutation status. Eligibility: Age 18-50, eumenorrheic, non-smokers, and body mass index (BMI) between 21 and 50 kg/m(2). 139 were randomized. Treadmill exercise: 150 or 300 min/week, five menstrual cycles. Control group maintained exercise <75 min/week. PRIMARY OUTCOME: Area under curve (AUC) for urinary estrogen. Secondary measures: urinary progesterone, quantitative digitized breast dynamic contrast-enhanced magnetic resonance imaging background parenchymal enhancement. Mean age 34 years, mean BMI 26.8 kg/m(2). A linear dose-response relationship was observed such that every 100 min of exercise is associated with 3.6 % lower follicular phase estrogen AUC (linear trend test, p = 0.03). No changes in luteal phase estrogen or progesterone levels. There was also a dose-response effect noted: for every 100 min of exercise, there was a 9.7 % decrease in background parenchymal enhancement as measured by imaging (linear trend test, p = 0.009). Linear dose-response effect observed to reduce follicular phase estrogen exposure measured via urine and hormone sensitive breast tissue as measured by imaging. Future research should explore maintenance of effects and extent to which findings are repeatable in lower risk women. Given the high benefit to risk ratio, clinicians can inform young women at increased risk that exercise may blunt estrogen exposure while considering whether to try other preventive therapies.

Exercise-Induced Dose-Response Alterations in Adiponectin and Leptin Levels Are Dependent on Body Fat Changes in Women at Risk for Breast Cancer.

BACKGROUND: Dysregulation of adipokines, such as adiponectin and leptin, is associated with a variety of chronic diseases, including cancer. Physical activity protects against breast cancer and one of the mechanisms which may underlie this association is exercise-induced changes in adipokine levels. The WISER Sister Trial was a three-armed randomized controlled trial in premenopausal women (n = 137) with an elevated risk for breast cancer. METHODS: A 5-menstrual-cycle-long dosed aerobic exercise intervention compared low-dose exercise (150 min/wk; n = 44) or high-dose exercise (300 min/wk; n = 48) with a control group asked to maintain usual activity levels (n = 45). Exercise intensity progressed to and was maintained at 70% to 80% of age predicted heart rate max. Body composition and adipokine levels were measured at baseline and follow-up. RESULTS: We observed significant linear trends for increased fitness capacity (Δ%: -2.0% control, 10.1% low dose, 13.1% high dose), decreased fat tissue-to-total tissue mass (Δ%: 0.7% control, -2.9% low dose, -3.7% high dose), increased body fat adjusted adiponectin (Δ%: -0.6% control, 0.6% low dose, 0.9% high dose), and decreased body fat adjusted leptin (Δ%: 0.7% control, -8.2% low dose, -10.2% high dose). CONCLUSIONS: In this randomized clinical trial of premenopausal women at risk for breast cancer, we demonstrate a dose-response effect of exercise on adiponectin and leptin and that dose response is dependent on changes in body fat. IMPACT: Improved adipokine levels, achieved by aerobic exercise training-induced decreases in body fat, may decrease breast cancer risk for high-risk premenopausal women. Cancer Epidemiol Biomarkers Prev; 25(8); 1195-200. ©2016 AACR.

Women In Steady Exercise Research (WISER) Sister: study design and methods.

PURPOSE: Women at elevated risk for breast cancer are motivated to reduce their risk. Current approaches rely primarily on hormonal intervention. A preventive exercise intervention might address the same hormonal issues, yet have fewer serious side effects and less negative impact on quality of life as compared to prophylactic mastectomy. WISER Sister was a randomized controlled trial which examined effects of two doses of exercise training on endogenous sex hormone exposure, hormonally active breast tissue, and other breast cancer risk factors. METHODS: Subjects for this single site trial were recruited from across the U.S., in collaboration with organizations that serve women at elevated risk, via emails, flyers, and letters. Eligibility criteria included age ≥ 18, eumenorrheic, and at elevated risk for breast cancer (e.g. BRCA1 or BRCA2 mutation and/or ≥ 18% lifetime risk according to prediction models). A 1:1:1 randomization scheme was used to allocate participants into: control, low dose (150 min/week), or high dose (300 min/week) home based treadmill exercise. Participants provided first morning urine samples daily for two menstrual cycles at study beginning and end for calculation of endogenous hormone exposure. In addition, women completed breast dynamic contrast enhanced magnetic resonance imaging, a fasting blood draw, a treadmill exercise test, and surveys at baseline and follow-up. DISCUSSION: WISER Sister randomized 139 women, 122 of whom completed the study. The overall drop-out rate was 12%. Findings will be useful in understanding the potential for exercise to assist with reducing risk for breast cancer among women at elevated risk.

A hybrid effectiveness-implementation trial of an evidence-based exercise intervention for breast cancer survivors.

BACKGROUND: The primary aims of this hybrid Type 1 effectiveness-implementation trial were to quantitatively assess whether an evidence-based exercise intervention for breast cancer survivors, Strength After Breast Cancer, was safe and effective in a new setting and to qualitatively assess barriers to implementation. METHODS: A cohort of 84 survivors completed measurements related to limb volume, muscle strength, and body image at baseline, 67 survivors completed measurements 12 months later. Qualitative methods were used to understand barriers to implementation experienced by referring oncology clinicians and physical therapists who delivered the program. RESULTS: Similar to the efficacy trial, the revised intervention demonstrated safety with regard to lymphedema, and led to improvements in lymphedema symptoms, muscular strength, and body image. Comparison of effects in the effectiveness trial to effects in the efficacy trial revealed larger strength increases in the efficacy trial than in the effectiveness trial (P < .04), but few other differences were found. Qualitative implementation data suggested significant barriers around intervention characteristics, payment, eligibility criteria, the referral process, the need for champions (ie, advocates), and the need to adapt during implementation of the intervention, which should be considered in future dissemination and implementation efforts. CONCLUSIONS: This trial successfully demonstrated that a physical therapy led strength training program for breast cancer survivors can be implemented in a community setting while retaining the effectiveness and safety of the clinical trial. However, during the translation process, strategies to reduce barriers to implementation are required. This new program can inform larger scale dissemination and implementation efforts.