: Psilocybin-assisted therapy (PAT) is a promising intervention to alleviate existential distress among patients with advanced cancer receiving palliative care. However, evidence on how to integrate PAT into routine oncology and palliative care services remains scarce. This study aimed to examine real-world PAT implementation, identify factors influencing adoption, and estimate integration costs within oncology and palliative care services.: We conducted a single-case implementation study in a large university-affiliated tertiary care center in Canada during the first year following its introduction. Semi-structured interviews with clinicians, managers, and other stakeholders explored barriers, facilitating conditions, and actions needed to support PAT implementation. A budget impact analysis estimated incremental costs associated with delivering PAT.After one year, no patients had received PAT. Ten professionals representing diverse clinical and managerial roles participated in the interviews. While participants viewed PAT favorably, they emphasized the need to align the intervention with existing care pathways and clarify referral processes. Administrative and regulatory procedures, together with logistical constraints related to treatment delivery, were identified as key barriers, whereas perceived clinical relevance and institutional leadership were seen as important facilitators. From the health care system perspective, the estimated cost of delivering a complete PAT intervention ranged from 2648 to 5827 Canadian dollars (CAD) per patient, depending on the scenario examined, excluding the cost of the psilocybin itself.: Despite perceived clinical relevance and relatively modest estimated costs, the absence of treated patients after one year highlights the gap between regulatory authorization and effective service uptake. These findings underscore the importance of structured implementation strategies, sustained institutional support, and alignment between regulatory frameworks and clinical workflows to ensure meaningful integration of PAT into routine oncology and palliative care services. Background/Objectives Methods Results: Conclusions
