A group of people, each diagnosed with an incurable cancer, gather in the great hall of a rustic retreat center surrounded by meadows and mountain views. In a brief opening ritual, they voice their intentions for the session and take a 25-mg dose of psilocybin. Ethereal music dissolves into the space as facilitators attentively drift among them, offering gentle presence and support as needed during the seven-hour session.
A participant later reflects, “I objectified my cancer and wanted to be angry at it and yell and scream and then started laughing at how absurd that was. So I gave it a hug and loved and forgave.”
Facing a cancer diagnosis can feel like stepping into a storm of uncertainty, isolation, and fear, leaving many patients grappling with profound emotional and existential distress. Conventional psychotherapy and pharmaceutical interventions often fall short in relieving these overwhelming feelings of anxiety and depression.
Psilocybin-assisted therapy has emerged as a safe and effective approach for addressing several mental health conditions, including cancer-related distress. Psilocybin, a naturally occurring psychedelic compound from Psilocybe mushrooms, temporarily alters perception and consciousness and can incite lasting, fundamental shifts in how people relate to anxiety, depression, and even mortality itself.
Dr. Anthony Back, an oncologist and palliative medicine physician from the University of Washington, remarks in a personal reflection, "The studies about the use of psilocybin-assisted psychotherapy for existential fear intrigued me. I do not have anything in my therapeutic pocket that is remotely as impactful as what these studies and anecdotes describe.”
In most treatment models, psilocybin is administered to individuals in carefully controlled settings under the supervision of two therapists. Additional preparation and integration sessions help patients clarify their intentions and make sense of their experiences. Altogether, this approach can require up to 30 hours of direct therapist contact for a single patient, making it resource-intensive and unfeasible to scale up to meet the needs of the hundreds of thousands of people who die of cancer in the US each year.
A group format could expand access to this transformative therapeutic intervention and may even offer additional benefits through connection with others facing similar challenges.
A recent study led by Dr. Back, published in Psychedelic Medicine, explores this idea by designing and testing a group retreat model for psilocybin therapy to relieve cancer-associated anxiety and depression.
The team conducted a series of eight retreats, each including two virtual preparation sessions, a three-day in-person retreat with a psilocybin session on the second day, and two virtual integration sessions. Each session was thoughtfully designed, incorporating group discussions to encourage equal participation and attentive listening, and structured rituals that helped anchor and provide meaning to intense or transcendent moments. Facilitators primarily served as guides and witnesses, rather than as therapists, throughout the process.
Although psilocybin itself has a strong safety profile, group administration raises an important practical question: how should the group be configured to ensure that there are enough facilitators available to provide one-on-one support if participants become distressed during the psilocybin session?
To address this question, each retreat included four core facilitators and two backup facilitators who were able to step in if needed. The study began with five participants in the first retreat, and after reviewing safety outcomes, the number of participants was gradually increased in subsequent cohorts, up to a maximum of eight participants.
Across all eight retreats, involving a total of 52 participants, there wasn’t a single instance of unattended participant distress that required involvement of the backup facilitators, demonstrating that a group configuration with four facilitators and eight participants is both feasible and safe.
To explore the efficacy of the group model, participants completed a series of psychological questionnaires. The results showed clinically meaningful reductions in anxiety and depression, comparable to those reported in studies of individual psilocybin therapy, and the improvements persisted for at least six months. Participants also reported reduced demoralization and death-related distress, along with improved psychosocial functioning and quality of life.
In personal reflections, participants described the group setting and ritualized structure of the retreat as factors that helped create a sense of calm and shared purpose, preparing them for both the psilocybin experience and the process of integration afterward. This communal element echoes a long history of psilocybin use in ceremonial settings, rooted in Indigenous Mesoamerican traditions, evoking the idea that the social and ritual contexts in which psilocybin is experienced may fundamentally contribute to, or perhaps even underly, the healing benefits of the medicine.
This is the first FDA-approved study of a ritual-based group model for psilocybin therapy. Although conducted within the framework of a clinical trial, this work brushes up against experiences of transcendence, collective connection, and spirituality – dimensions for which we lack the robust tools, metrics, and language to fully assess and integrate into current scientific and medical paradigms.
Still, the study marks an important first step forward, establishing parameters for safe group psilocybin therapy and showing promising efficacy outcomes. By refining and documenting the retreat procedures, the researchers have created a model that could be scaled and studied further, toward the goal of expanding access to psilocybin therapy and offering new ways to relieve the psychological suffering that can accompany serious illnesses like cancer.
Fred Hutch/University of Washington/Seattle Children’s Cancer Consortium Members Drs. Anthony Back and Ted Gooley contributed to this research.
The spotlighted research was funded by the Steven and Alexandra Cohen Foundation.
Back AL, McGregor BA, Thorn LL, Baker K, Gooley T, Kaelen M, Harvey K, Guy JM, Myers S, Perez J, Thompson P, Billingsley L, and Sesnon C. 2026. Group Retreat Psilocybin Therapy for People with Metastatic Cancer with Symptoms of Anxiety and Depression: Safety and Efficacy Outcomes of a Phase 1/2 Study. Psychedelic Medicine. DOI: 10.1177/28314425251413856
Science Spotlight writer Thamiya Vasanthakumar is a postdoctoral research fellow in the Campbell Lab at Fred Hutch. As a structural biologist, she uses cryogenic electron microscopy (cryoEM) to visualize the molecular structures of receptors found on the surface of immune cells.
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