Effectiveness of acceptance and commitment therapy for mental illness in cancer patients: A systematic review and meta-analysis of randomised controlled trials.

BACKGROUND Disease awareness is an important aspect of psychological adjustment in cancer patients; however, there is limited evidence that acceptance and commitment therapy (ACT) is recommended for the treatment of mental illness in cancer patients. PURPOSE To assess the effectiveness of ACT for cancer patients with mental illness. METHODS Ten databases were searched for publications up to July 25, 2020, using combinations of search terms related to mental health, cancer, and randomised controlled trials (RCTs). Two researchers independently screened the literature, extracted data, and assessed the quality of the study. RESULTS Seventeen RCTs (877 cancer patients) were mainly of low quality, compared with control group, ACT was associated with improved outcomes after treatment completion and at 1-3 months and at 3-6 months of follow-up for depression (Standardised mean difference [SMD] = -0.93, 95% CI, -1.36 to -0.51, P < .001), anxiety (SMD = -1.22, 95% CI, -2.16 to -0.29, P = .01), quality of life (SMD = 0.85, 95% CI, 0.17 to 1.11, P = .01), psychological distress (SMD = -0.80, 95% CI, -1.24 to 0.35, P < .001), and stress (SMD = -0.54, 95% CI, -1.02 to -0.07, P = .03). After 6 months of follow-up, depression, anxiety, quality of life, and stress were still significant. ACT was associated with psychological flexibility and was not associated with a reduction in fear at treatment completion. However, psychological flexibility (1-3 months) decreased and fear (1-6 months) decreased, and the longer-term effect was still significant. CONCLUSION ACT can be an important component of future cancer care, as it may alleviate depression, anxiety, stress, and fear, and improve quality of life. However, further research is required to determine long-term treatment effects. High-quality RCTs are needed to more reliably estimate treatment effects.