Inclusion Criteria:  Participant or participant's legally authorized representative has the ability to understand and the willingness to provide a signed and dated informed consent form. Participant is ≥ 18 years of age. Participant had/has a scheduled appointment with oncology or neurosciences services at the participating medical and surgical facility.  Participant is characterized by at least one of the following criteria:  Has a neurological complication from any type of cancer, or is under evaluation for a possible cancer diagnosis or neurologic complication. Participant may be newly diagnosed, in relapse, or be free of disease at the time of recruitment. Participant without a confirmed cancer diagnosis is eligible.; OR Has a neurological disorder, or is under evaluation for a possible diagnosis of a neurological disorder; OR Does not meet the characteristic of either a. or b. above. This participant would be considered a "healthy control" for cancer and neurological disorders.  Exclusion Criteria:  Participant or participant's legally authorized representative is unable to provide informed consent.