Mindfulness-based stress reduction for breast cancer survivors (MBSR(BC)): evaluating mediators of psychological and physical outcomes in a large randomized controlled trial.

MBSR(BC) is known to have a positive impact on psychological and physical symptoms among breast cancer survivors (BCS). The cognitive mechanisms of "how" MBSR(BC) works was addressed in a recent study that found that there was strong consistent evidence that reduced emotional reactivity is a mediator and moderate consistent evidence that mindfulness, rumination, and worry were mediators. 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 mediators of 6- and 12-week outcomes were identified by analysis of covariance (ANCOVA), followed by formal mediational analyses of main effects of MBSR(BC) on 6- and 12-week outcomes, including percentage of total effects explained. 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). TRIAL REGISTRATION: Registration Number: NCT01177124 http://www.ClinicalTrials.gov.

Fatigue, anxiety, and quality of life in breast cancer patients compared to non-cancer controls: a nationwide longitudinal analysis.

PURPOSE: Fatigue and anxiety are common and significant symptoms reported by cancer patients. Few studies have examined the trajectory of multidimensional fatigue and anxiety, the relationships between them and with quality of life. METHODS: Breast cancer patients (n = 580) from community oncology clinics and age-matched controls (n = 364) completed fatigue and anxiety questionnaires prior to chemotherapy (A1), at chemotherapy completion (A2), and six months post-chemotherapy (A3). Linear mixed models (LMM) compared trajectories of fatigue /anxiety over time in patients and controls and estimated their relationship with quality of life. Models adjusted for age, education, race, BMI, marital status, menopausal status, and sleep symptoms. RESULTS: Patients reported greater fatigue and anxiety compared to controls at all time points (p's < 0.001, 35% clinically meaningful anxiety at baseline). From A1 to A2 patients experienced a significant increase in fatigue (ß = 8.3 95%CI 6.6,10.0) which returned to A1 values at A3 but remained greater than controls' (p < 0.001). General, mental, and physical fatigue subscales increased from A1 to A2 remaining significantly higher than A1 at A3 (p < 0.001). Anxiety improved over time (A1 to A3 ß = - 4.3 95%CI -2.6,-3.3) but remained higher than controls at A3 (p < 0.001). Among patients, fatigue and anxiety significantly predicted one another and quality of life. Menopausal status, higher BMI, mastectomy, and sleep problems also significantly predicted change in fatigue. CONCLUSION: Breast cancer patients experience significant fatigue and anxiety up to six months post-chemotherapy that is associated with worse quality of life. Future interventions should simultaneously address anxiety and fatigue, focusing on mental and physical fatigue subdomains.