The Promoting Activity in Cancer Survivors (PACES) trial: a multiphase optimization of strategy approach to increasing physical activity in breast cancer survivors

Background: Despite the significant, empirically supported benefits of physical activity, the majority of breast cancer survivors do not meet recommended guidelines for physical activity. A variety of effective strategies to increase physical activity in breast cancer survivors have been identified. However, it is unknown which of these strategies is most effective or how these strategies might be combined to optimize intervention effectiveness. Methods: The proposed trial uses multiphase optimization strategy (MOST) to evaluate four evidence-based intervention strategies for increasing physical activity in breast cancer survivors. We will enroll 500 breast cancer survivors, age 18 and older, who are 3-months to 5 years post-treatment. Using a full-factorial design, participants will be randomized to receive a combination: 1) supervised exercise, 2) facility access, 3) self-monitoring, and 4) group-based active living counseling. The primary outcome, moderate-to-vigorous physical activity (MVPA) will be measured at baseline, 3 months, and 6 months using an Actigraph GT3X+. To evaluate intervention effects, a linear mixed-effects model will be conducted with MVPA as the outcome and with time (3 months and 6 months) as the within-subjects factor and intervention (i.e., supervised exercise, facility access, self-monitoring, and active living counseling) as the between subjects factor, along with all two-way interactions. Discussion: The purpose of the PACES study is to evaluate multiple strategies for increasing physical activity in breast cancer survivors. Results of this study will provide in an optimized intervention for increasing physical activity in breast cancer survivors.