L-Theanine to Support Relaxation and Mood for Cancer Patients in Surveillance

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative. * Assent, when appropriate, will be obtained per institutional guidelines * Willingness to comply with all study interventions including the use of L-theanine and follow-up assessments * Age: ≥ 18 years * Ability to read and understand English or Spanish for questionnaires * Patients must be a cancer patient who has completed treatment and has been in surveillance for at least 6 months * Participants must not have used any herbs or supplements in the past 30 days * Participants must report an anxiety score of \> 3 on Visual Analog Scale - Anxiety * Participants must not have had any changes to their psychiatric medications within the past 60 days * Women of childbearing potential (WOCBP): negative urine or serum pregnancy test. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required * Agreement by females and males of childbearing potential to use an effective method of birth control or abstain from heterosexual activity for the course of the study through at least 1 month after the last dose of protocol therapy. * Childbearing potential defined as not being surgically sterilized (men and women) or have not been free from menses for \> 1 year (women only) Exclusion Criteria: * Concurrent use of other alternative medicines, including herbal agents and high-dose vitamins and minerals, unless taken to correct a …