Inclusion Criteria:

- Women aged 18 years or older

- Diagnosis of breast cancer, confirmed by histopathology; Stages 0, I, II, IIIA, or
IIIB

- Clinical diagnosis of Major Depressive Disorder (DSM-IV-TR)

- Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983) depression subscale
score of 11 or greater

- Montgomery Asberg Depression Rating Scale (MADRS; Montgomery and Asberg, 1979) score
of 25 or greater at Screening and Baseline visits

- Use of antidepressants in a previous episode of major depression or in the past for
any other indication does not affect the patient’s inclusion in this study.

- During the current episode of major depressive disorder, as stated in the Exclusion
criteria, failure to respond to one or more adequate trials of an antidepressant will
exclude the patient from the study since this is not a study of “treatment-resistant
depression”.

- During the study, the patient may not use any other antidepressants.

Exclusion Criteria:

- Presence of another current clinically significant Axis I disorder like bipolar
disorder, schizophrenia, or panic disorder

- Current (in past 6 months) comorbid active substance abuse or dependence

- Failure to respond to one or more adequate trials of an antidepressant in the current
episode of MDD

- A reduction in MADRS score of 20% or greater from Screening to Baseline visit

- Clinically significant laboratory abnormalities that in the judgment of the
Investigator would increase risk of adverse effects with bupropion

- Pregnant or lactating women

- History of an eating disorder, seizures, head injury, or other intracranial pathology
because these conditions are usually contraindications to the use of bupropion XL

- Previous allergy or intolerance to bupropion

- Patients judged to be at significant suicidal risk