Measures were collected at baseline and after the intervention by assessors who were blind to the study condition. Primary outcome measures were mood and diurnal salivary cortisol slopes. Secondary outcomes were stress symptoms, quality of life, and social support.
Using linear mixed-effects models, in intent-to-treat analyses, cortisol slopes were maintained over time in both SET (P = .002) and MBCR (P = .011) groups relative to the control group, whose cortisol slopes became flatter.
Women in MBCR improved more over time on stress symptoms compared with women in both the SET (P = .009) and control (P = .024) groups. Per-protocol analyses showed greater improvements in the MBCR group in quality of life compared with the control group (P = .005) and in social support compared with the SET group (P = .012).
This study, the largest trial to date, concludes that MBCR was superior for improving a range of psychological outcomes for distressed survivors of breast cancer. Both the SET and MBCR also resulted in more normative diurnal cortisol profiles than the control condition.