RESUMO
BACKGROUND: The aim of this clinical single group pilot study was to assess mental well-being, psychological symptoms, and a set of stress biomarkers among breast cancer survivors with high depressive symptoms undergoing the Mindfulness-Based Stress Reduction (MBSR) program. METHODS: Participants included 23 curatively treated breast cancer survivors from the Helsinki University Central Hospital with clinically significant symptoms of depression (Beck Depression Inventory > 13, and assessed by a psychiatrist), at 1-year post-operative follow-up. Mental wellbeing and psychological symptoms were assessed with self-reported questionnaires (Resilience Scale, Self-Compassion Scale, Five Facet Mindfulness Questionnaire, World Health Organization Quality of Life-questionnaire, Perceived Stress Scale, Beck Depression Inventory, Beck Anxiety Inventory, Insomnia Severity Index); in addition, stress response was assessed with biomarkers (cortisol, adrenocorticotropine, and high-sensitivity-CRP from blood; 24 h-cortisol from urine). All measures were addressed at baseline, mid-program (4 weeks after baseline) and at the completion of the 8-week MBSR program. Engagement to the independent mindfulness home practice was collected with a diary. RESULTS: From baseline to the completion of the 8-week MBSR program, we observed significant increases in resilience (d = 0.60, p = 0.005), and quality of life (d = 0.92, p = 0.002), and significant reductions in symptoms of depression (d = - 1.17, p < 0.0001), anxiety (d = - 0.87, p < 0.0001), insomnia (d = - 0.58, p = 0.006), and marginally significant reduction in perceived stress (d = - 0.40, p = 0.09). We found no changes in self-compassion or mindfulness skills, nor in the stress biomarkers during or at the completion of the program. There was no association between the engagement time to the independent mindfulness practice and any of the outcomes. CONCLUSIONS: Attending the MBSR program was associated with increased wellbeing and reduced psychological symptoms in breast cancer survivors with clinically significant symptoms of depression. However, these favorably experienced changes did not transfer to the level of stress biomarkers during the 8-week program. Lack of association between the engagement in the mindfulness home practice and change in outcomes suggests that in the studied range of practice time, other qualities of MBSR despite the amount of independent practice may have a more important role for the improved wellbeing. Trial registration ISRCTN12326308 at 16/02/2021, retrospectively registered.