Individual and Group Psilocybin-Assisted Therapy for Cancer-Related Distress: A Mixed-Methods Systematic Review

Abstract

Aim. Psilocybin-assisted therapy (PAT) shows innovation in palliative care by meeting patients' existential and spiritual needs. However, its underlying mechanisms and ideal setting remain unclear. This review aims to summarize literature on individual and group PAT for cancer patients, combining quantitative and qualitative evidence to clarify its effectiveness, mechanisms, and optimal context of intervention for this population. Method. A mixed-method systematic review with a convergent segregated approach was conducted following the Joanna Briggs Institute methodology (JBI). After a systematic search on four main databases, 14 papers (eight quantitative, four qualitative, and two mixed-methods) were included considering the criteria. Methodological quality was assessed with JBI Critical Appraisal Tools, and data was extracted into customized tables. Quantitative and qualitative findings were independently and narratively synthesized, then integrated into a final analysis. Results. Both forms of evidence aligned. Quantitative studies reported safe, acute and lasting improvements in depression, anxiety, existential distress, suicidal ideation, loss of meaning, spirituality, and quality of life following a single psilocybin dose. Most patients found PAT deeply meaningful, producing positive effects mediated by mystical experiences, but not in the long-term. Qualitative reports revealed additional mechanisms such as connectedness, emotional breakthroughs, and acceptance. Group-PAT demonstrated feasibility and amplified therapeutic feelings, offering a more accessible and cost-effective option. Restricted data on other contextual factors limited the analysis. Conclusions. PAT improves cancer patients' well-being by helping them facing death. Clinicians need to create environments that foster the proposed mechanisms. Researchers should explore them and compare individual vs. group settings in better-designed trials.