Psilocybin in Cancer Pain Study

Inclusion Criteria: * Participants must be 18 year old or older; * Participants must have advanced cancer, defined as a cancer that is unlikely to be cured or controlled with treatment; * Participants must have progressed on or be intolerant to approved therapies with a known clinical benefit (unless it is documented that they have refused such treatments); * Participants must evaluate their average pain on BPI Severity Scale ≥ 4/10 over the past week; * Participants must receive chronic opioid pharmacotherapy for pain with an Oral Morphine Equivalent (OME) ≥ 200mg/day; * Participants must have been seen by a palliative care clinician either at DFCI, MGH or associated satellites in the last three months; * Participants must have an ECOG Performance Status ≤ 2 * Participants must meet the following organ and marrow function on their last available bloodwork as defined below: * Platelets ≥ 50,000/mcL * AST(SGOT)/ALT(SGPT) ≤ 5 × institutional ULN * Participants must be able to understand and willing to sign a written informed consent document * Participants must be able to swallow pills. * Participants must provide a contact (relative, spouse, close friend or other support person) who is willing and able to be reached by the investigators in the event of a participant becoming suicidal or unreachable. * Participants must agree to inform the investigators within 48 hours of any new medical conditions and procedures. * Participants must agree to the following lifestyle modif…