The purpose of this research is to study the safety and effects of single-dose psilocybin
25mg versus an active placebo (single dose psilocybin 1mg) in the treatment of anxiety,
depression, and existential distress (i.e. loss of meaning and hope; fear of death) in
advanced cancer (i.e. stage 3 or 4). Study medications will be administered in conjunction
with brief psychotherapy that is designed to treat anxiety, depression and existential
distress in advanced cancer.