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.