Inclusion Criteria:
* Diagnosis with advanced-stage cancer (usually meaning inoperable or incurable) with a life expectancy of less than 12 months.
* Anxiety as a result of cancer diagnosis
* Failure to respond adequately or at all to medication intended to reduce anxiety, or have refused to take anxiolytic medication.
* Completed or independently decided to end all direct cancer treatments, such as chemotherapy and radiation, two weeks prior to the first experimental (MDMA) session. If subjects wish to initiate or resume treatment for cancer at any point prior to the second experimental (MDMA) session, then they will be withdrawn from the study and will be asked to see the co-investigator oncologist for a final physical examination. Participants will not be withdrawn from the study if they initiate or resume treatment after the second experimental (MDMA) session. Those who are receiving cycles of cancer treatments for only palliative purposes (no longer for any curative reasons or to induce complete remission), may also be included in this study provided that they, as well, have completed their last cycle of treatment at least two weeks prior to the first experimental (MDMA) session and provided that they will not resume another cycle of treatment until after completion of the second experimental (MDMA) session. If a subject receiving palliative cancer treatment decides to receive a next cycle of this cancer treatment prior to the second experimental session, then, again, they will be withdrawn from the study. Participants will not be withdrawn from the study if they initiate or resume palliative cancer treatments after the second experimental (MDMA) session.
* Willing to commit to and follow all directions and restrictions relating to the study period
* Must be willing and able to discontinue use of psychiatric medication except that being used to treat anxiety. If still taking medication when enrolled to the study, medication will be discontinued long enough before the first MDMA-assisted psychotherapy session to avoid a drug-drug interaction
* Must be willing and able to stay overnight at the facility after each MDMA-assisted session.
* If seeing another psychotherapist, participants must be willing to give the principal investigator permission to communicate with him or her.
* Female participants of childbearing potential must have a negative pregnancy test and must agree to use an effective form of birth control.
Exclusion Criteria:
* People with a life expectancy of longer than 12 months
* Women who are pregnant or nursing, or of child bearing potential and are not practicing an effective means of birth control.
* People with any dissociative disorder, anorexia nervosa, bulimia nervosa, a primary psychotic disorder or affective disorder other than anxiety related to advanced stage cancer
* People diagnosed with abuse of or dependence on any substance (other than caffeine or nicotine) in the past 60 days.
* People with known primary or metastatic cancer of the CNS
* People with significant, unstable hematological, endocrine, cerebrovascular, cardiovascular, coronary, pulmonary, renal, gastrointestinal, immunocompromising, or neurological disease, including seizure disorder, that in the clinical judgment of the investigators poses too great a potential for side-effects.
* People with significant peripheral vascular disease, hepatic disease, renal insufficiency, or preexisting or past evidence of hyponatremia.
* People diagnosed with hypertension, even if well-controlled with medication. A systolic blood pressure of 140 or greater and/or a diastolic blood pressure of 90 or greater will exclude the potential participant from this study.
* People with liver enzyme values indicative of severely compromised hepatic (liver) function
* People who weigh less than 45 kg (98 lb)
* People reporting a history of use of "ecstasy" (illicit drug preparations purported to contain MDMA) at any time within the previous 3 months.
* People reasonably judged to present a serious suicide risk or who are likely to require psychiatric hospitalization during the course of the study
* People requiring psychotropic medication other than anxiolytic medication or for pain control