Eligibility Criteria
* 21 to 85 Years of age
* Diagnosis of Stage I, II or III cancer
* Histologically-proven malignancy
* Receiving or within one year of having received cancer treatment with radiation and/or chemotherapy
* Montgomery and Åsberg Depression Rating Scale (MADRS) ≥ 20 (moderate to severe depressive symptoms)
* Duration of depressive symptoms ≥ 2 weeks by patient report.
* No active/acute suicidality requiring immediate care or psychiatric hospitalization
* Sufficient English language proficiency to complete all assessments without assistance
* Able to swallow pills
* No severe anemia, defined as hemoglobin \< 10 g/dL
* No history of multiple adverse drug reactions or allergy to study drugs
* Not pregnant
* No history of head trauma
* No history of epilepsy
* No other concurrent antidepressant medications
Exclusion Criteria
* Have a current or previous diagnosis of or history consistent with obsessive-compulsive disorder, posttraumatic stress disorder, bipolar I or II, manic or hypomanic episodes, schizophrenia, major Axis II disorders which might compromise the study, or major depression with psychotic symptoms, as assessed using the MINI International Neuropsychiatric Interview (MINI Plus).
* Have a documented history of an intellectual disability.
* Use of any antidepressant medication in the last 2 weeks before visit 1 (4 weeks for fluoxetine).
* Currently being treated with tamoxifen.
* Subjects who were non-responsive to two or more courses of antidepressant medications given at an adequate dosage\* for symptom treatment within four weeks, or by the judgment of the investigator considered to have treatment resistant depression (TRD), or a history of electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS) or psychosurgery within the last year.
* Have a history of any seizure disorder.
* Any clinically significant abnormal vital sign, ECG, or laboratory values as determined by the investigator which might interfere with the study.
* Have a high suicidal risk as assessed using the Columbia-Suicide Severity Rating Scale (C-SSRS). High suicidal risk is indicated by:
1. A positive response to question 4 or 5, indicating endorsement of suicidal ideation with at least some intent to act in the past month; and/or
2. A positive response to part two of question 6, indicating the presence of any suicidal behavior in the past 3 months.
* Have a history of substance dependence/abuse\*\* within the past 6 months or a positive drug screen result during the screening period.
* Have a history of severe allergies to more than 1 class of medication or multiple adverse drug reactions.
* \* An adequate dosage of the antidepressant medication is defined as the average of the usual dose (mg/day) recommended in American Psychiatric Association (APA) Practice Guideline for the Treatment of Patients with Major Depressive Disorder, Third Edition. E.g. the usual dose of Citalopram is 20-60 mg/day, the adequate dosage is 40 mg/day.
* \*\* Tobacco is excluded here, and alcohol abuse is defined as average pure alcohol intake is more than 112 g (for male) or 56 g (for female) per week and/or with Alcohol withdrawal syndrome. Pure alcohol intake =% (Concentration or alcohol content) x c.c. (volume)x 0.79 (density of alcohol). Result of serum ethanol test should be equal to or lower than 10.0 mg/dL to be determined as eligible for the trial. If test result is between 10.1 to 29.9 mg/dL, only one re-test is allowed per subject to meet the criterion. Subject with test result equal to or higher than 30.0 mg/dL is to be excluded.