Therapeutic use of classic psychedelics to treat cancer-related psychiatric distress

Cancer is highly prevalent and one of the leading causes of global morbidity and mortality. Psychological and existential suffering is common in cancer patients, associated with poor psychiatric and medical outcomes. Promising early-phase clinical research (1960s to early 1970s) suggested a therapeutic signal for serotoninergic psychedelics (e.g. psilocybin, LSD) in treating cancer-related psychiatric distress. After several decades of quiescence, research on psychedelic-assisted therapy to treat psychiatric disorders in cancer patients has resumed within the last 2 decades in the US and Europe. This review article is based on a systematic search of clinical trials from 1960–2018 researching the therapeutic use of psychedelic treatment in patients with serious or terminal illnesses and related psychiatric illness. The search found 10 eligible clinical trials, with a total of 445 participants, with the vast majority of the patients having advanced or terminal cancer diagnoses. Six open label trials, published between 1964 and 1980 (n = 341), suggested that psychedelic therapy (mostly with LSD) may improve cancer-related depression, anxiety, and fear of death. Four RCTs trials were published between 2011 and 2016 (n = 104), mostly with psilocybin treatment (n = 92), and demonstrated that psychedelic-assisted treatment can produce rapid, robust, and sustained improvements in cancer-related psychological and existential distress.