Mindfulness-Based Stress Reduction for Breast Cancer Survivors (MBSR (BC)): Evaluating Mediators of Psychological and Physical Outcomes in a Large Randomized Controlled Trial

ABSTRACT MBSR(BC) is known to have a positive impact on psychological and physical symptoms among breast cancer survivors (BCS). However, the cognitive mechanisms of “how” MBSR(BC) works are unknown. The purpose of this study, as part of a larger R01 trial, was to test whether positive effects achieved from the MBSR(BC) program were mediated through changes in increased mindfulness, decreased fear of breast cancer recurrence, and perceived stress. Female BCS >21 years diagnosed with Stage 0-III breast cancer were randomly assigned to a 6-week MBSR(BC) or a Usual Care(UC) regimen. Potential outcome mediators were identified by use of an analysis of covariance (ANCOVA), comparing mean values of outcome variables and potential mediating variables followed by mediational and bootstrap analyses. Among 322 BCS (167 MBSR(BC) and 155 UC), fear of recurrence and perceived stress, but not mindfulness, mediated reductions in anxiety and fatigue at weeks 6 and 12, partially supporting our hypothesis of cognitive mechanisms of MBSR(BC). Support: This study was supported by the National Cancer Institute (Award Number 1R01 CA131080-01A2). This work also has been supported in part by the Biostatistics and Bioinformatics Shared Resource at the H. Lee Moffitt Cancer Center & Research Institute, an NCI designated Comprehensive Cancer Center (P30-CA076292). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health. This study protocol was approved by the Institutional Review Board at the University of South Florida to ensure the ethical treatment of participants. Conflict of Interest: The authors have no conflicts to report. Trial Registration: www.ClinicalTrials.gov Registration Number: NCT01177124