Mindfulness-Based Cognitive Therapy for Anxiety, Depressive Symptoms and Psychological Distress in Women with Breast Cancer: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background/Objectives: Psychological distress, anxiety, depressive symptoms and fear of cancer recurrence affect many women treated for breast cancer and often persist beyond active treatment. Mindfulness-based cognitive therapy (MBCT) is manualised and can be delivered in groups or over the internet, which makes it a candidate component of personalised supportive care, but its effect has not been quantified separately from that of other mindfulness programmes. We estimated the association between MBCT, including internet-delivered formats, and four psychological outcomes in adult women with breast cancer and rated the certainty of the evidence. Methods: This study represents a systematic review and meta-analysis of parallel-group randomised controlled trials, reported in accordance with the PRISMA 2020 statement. PubMed/MEDLINE, Scopus, Web of Science Core Collection and Embase were searched from inception without language restriction. The search was updated on 17 September 2026 in PubMed/MEDLINE, Scopus and Web of Science Core Collection; Embase, searched in the original search, could not be included in the update because its records could not be exported and institutional access subsequently ended; this is reported as a limitation. Trials were eligible when participants with breast cancer could be identified separately or, where they could not, when at least 90% of randomised participants were women with breast cancer, a threshold defined before data extraction. Two reviewers independently screened records, extracted post-intervention data directly from the published tables of each trial and appraised risk of bias with the Cochrane Risk of Bias 2 tool. We fitted random-effects models (restricted maximum likelihood); Hartung–Knapp intervals, fixed-effect estimates and a synthesis restricted to trials enrolling women with breast cancer only were sensitivity analyses defined before data extraction. Certainty was rated with GRADE. Results: Three trials (353 randomised participants, 340 of them women with breast cancer; one trial randomised 137 women with breast cancer and 13 men with prostate cancer and did not report results separately by tumour type) from Japan and Denmark were included; no outcome was informed by more than two trials. MBCT was associated with reductions in anxiety (Hedges’ g = −0.69, 95% CI −1.25 to −0.13; two trials, 182 participants) and in depressive symptoms (g = −0.90, 95% CI −1.46 to −0.35; two trials, 182 participants). Associations with total psychological distress (mean difference −5.09, 95% CI −10.20 to 0.02; two trials, 178 participants) and with fear of cancer recurrence, which rested on one trial, were imprecise and compatible with no benefit. Hartung–Knapp intervals included no effect for every outcome, and the anxiety and depressive-symptom analyses reduced to a single trial when the trial with a mixed cancer population was excluded, so neither apparent effect was robust to the method used to quantify uncertainty. Certainty was very low for all four outcomes. Conclusions: MBCT is associated with moderate-to-large short-term reductions in anxiety and depressive symptoms, but each estimate rests on two trials, is not robust to the inferential method used and is of very low certainty; three trials are too few to support firm recommendations, and the programme should be regarded as promising rather than established. Adequately powered trials with active comparators, common outcome measures and longer follow-up are needed. Routine checking for redundant publication is also required: one retrievable report, classified as a suspected redundant report on numerical comparison alone, presents data largely identical to those of an included trial.