Patient Decision Aid in Supporting Decision-Making About When to Start or Stop New Drugs, Join Clinical Trials, or Continue Active Surveillance in Patients With Medullary Thyroid Cancer and Their Caregivers

Inclusion Criteria: * Aged 18 years old or older * Have or will face(d) this decision, including: Patient/survivor - who has medullary thyroid carcinoma, as determined by a clinician or documented in the Genetics of Endocrine Neoplasia Registry or sporadic (medullary thyroid carcinoma) MTC database; Caregiver/family member - of patient/survivor who has medullary thyroid carcinoma, as nominated by the patient/survivor; and Provider - who treats patients/survivors who have medullary thyroid carcinoma, as described above * Able to speak, read, and write English * Pregnant patients are included Exclusion Criteria: --Individuals with cognitive or psychological impairment (e.g., depression, anxiety, severe mental illness; as documented in the registry)