Behavioral Activation for Depression in Older Cancer Survivors

Inclusion Criteria: Phase I: * As per self-report or medical record, ≥65 years old * As per self-report or medical record, has a history of cancer * As per medical record and/or clinician confirmation: * a patient in MSK Survivorship Clinics AND/OR * no evidence of disease (NED) AND/OR * 6 months or more post-treatment (patients on maintenance hormonal therapies are eligible) * Fluent in English, as per self-reported fluency of "well" or "very well"\* * As per self-report, able to communicate over video-conference and/or phone for sessions * Elevated score on the PHQ-9: ≥5 (N/A for Training Case participants) * Received a Blessed Orientation-Memory-Concentration Scale (BOMC) score of ≤ 11 (N/A for Training Case participants) Phase II: * As per self-report or medical record, ≥18 years old * Fluent in English, as per self-reported fluency of "well" or "very well"\* * As per self-report or medical record, has a history of cancer * Elevated score on the PHQ-9: ≥5 * Received a Blessed Orientation-Memory-Concentration Scale (BOMC) score of ≤ 11 (N/A for Training Case participants) Note. The eligibility criteria for Phase II allows inclusion of younger participants and those receiving active treatment due to the theoretical rationale that a single-session intervention will remove certain barriers that are believed to exist for these groups in receiving the longer, 10-session intervention. Exclusion Criteria: Phase I: * As per PI determination, requires a higher level of care for current passive or active suicidal ideation than current protocol is able to provide. If a participant receives a score of \> 0 on item 9 of the PHQ-9, they will be referred to study PI for further evaluation. They will be excluded from participation in this study if the PI determines they would be appropriate for a higher level of care than BA may be able to provide. * As per self-report or as documented in the medical record, current untreated (e.g., no medication, no therapy) major psychotic disorder (schizotypal personality disorder, schizophreniform disorder, schizoaffective disorder). Patients diagnosed with a major psychiatric disorder will be reviewed by the study PI to determine eligibility prior to consent. * As per self-report or medical record, currently taking antidepressant medication for \< 3 month * As per medical record, patient has impaired decision-making capacity Phase II: * As per PI determination, requires a higher level of care for current active suicidal ideation than current protocol is able to provide. If a participant receives a score of \> 0 on item 9 of the PHQ-9, they will be referred to study PI for further evaluation. They will be excluded from participation in this study if the PI determines they would be appropriate for a higher level of care than BA may be able to provide. * As per self-report or medical record, current weekly psychotherapy or currently taking an antidepressant for \<3 months. * As per medical record, patient has impaired decision-making capacity * Language verification: Prior to enrollment, patients will be asked the following two questions by research staff to verify English fluency necessary for participation in the study: 1. How well do you speak English? (must respond "Well" or "Very well" when given the choices of Very well, Well, Not well, Not at all, Don't know, or Refused) 2. What is your preferred language for healthcare? (must respond English)