A Randomized Clinical Trial of Mindfulness-Based Stress Reduction Program Among Breast Cancer Survivors Post-Treatment: Evaluating Mediators of Cognitive Improvement.

Unlabelled: The Mindfulness-Based Stress Reduction program for breast cancer survivors (MBSR [BCs]) is a stress-reducing program designed to increase cognitive functioning through four meditational practices. This randomized clinical trial aimed to determine if improvements in cognitive functioning and perceived cognitive abilities achieved from the MBSR(BC) were mediated through increased mindfulness, decreased rumination, and decreased perceived stress. Breast cancer survivors (BCSs) who met inclusion criteria of stage I, II, or III BC and received either chemotherapy (CT) or both CT and radiation were randomized to either the 6-week MBSR(BC), or Breast Cancer Education Support (BCES) program, or to a usual care (UC) regimen. Analysis of covariance was first implemented to identify potential mediators, followed by a formal mediational analysis to evaluate the effects of MBSR(BC) on 6-, 12-, and 26-week outcomes. After consent, 212 BCS were randomized to MBSR(BC) ( = 91), BCES ( = 90), or UC ( = 31). The mean age was 56.5 and the majority of the BCS, 73.1%, were White and non-Hispanic. Results showed increases in "observing" as part of mindfulness as a potential mediator of MBSR(BC) effects on impairments on quality of life and logical memory at 6 months relative to UC. No mediation effects were identified for outcomes measured at 6 or 12 weeks and also when MBSR(BC) was compared with the BCES program. These results partially supported our hypothesis that improvement in cognitive functioning would occur through increased mindfulness. Although few mediating relationships were identified, results showed a relationship between mindfulness and cognitive functioning. Both mediating relationships occurred through increases in "observing," a subconcept of "mindfulness," when compared to the MBSR(BC) with UC at 6 months. This study shows that mediators may help "optimize" clinical therapeutic treatment effects, thus contributing to the advancement of science.

Trial Registration: ClinicalTrials.gov, www.

Clinicaltrials: gov.

Registration Number: NCT02786797.