Anxiety and quality of life will be measured at the start of the study, before each sessions of MDMA-assisted therapy, one week after receiving MDMA-assisted therapy and once at the end of the study, 84 days after a person started the study (approximately two months after the second MDMA-assisted psychotherapy session; for Stages 1 and 2). All study subjects will also receive a second medical examination 36 days after the study has begun (and again 36 days after starting Stage 2). The medical examination will be performed at the Lahey Clinic Medical Center's Medical Oncology department or at McLean Hospital.