Ask people where they want to die, and they will tell you at home, with their loved ones. But most of us die in an I.C.U. The biggest taboo in American medicine is the conversation about death. To a doctor, it’s a defeat to let a patient go.” Bossis and several of his colleagues described the considerable difficulty they had recruiting patients from N.Y.U. ’s cancer center for the psilocybin trials. “I’m busy trying to keep my patients alive,” one oncologist told Gabrielle Agin-Liebes, the trial’s project manager. Only when reports of positive experiences began to filter back to the cancer center did nurses there — not doctors — begin to tell patients about the trial.