Major depression (MD) is a psychiatric disorder characterized by a persistent feeling of sadness, anhedonia or a decreased perception of pleasurable experiences, as well as appetite alterations and weight variations, sleep disorders, altered psychomotor skills, fatigue, guilt, decreased self-worth, suicidal thoughts and difficulty concentrating in a task (1).

MD is a frequent complication in patients who are diagnosed with advanced cancer.

Inclusion Criteria:

1. Age: 18 to 65 years of age
2. Sex: Male or female
3. Major depressive disorder (MDD) diagnosis as per Diagnostic and Statistical Manual of Mental Disorders (DSM-5).
4. Palliative stage cancer diagnosis (advanced-disease stage)
5. Who can read and write in spanish
6. Eastern Cooperative Oncology Group (ECOG) 0-2
7. Karnofsky ≥ 50
8. Palliative prognostic index A
9. Not currently undergoing systemic oncologic treatment
10. Patients who agree to participate in the study by signing an informed consent.

Exclusion Criteria:

1. Comorbidities including other psychiatric diseases (additional to MDD, generalized anxiety or panic disorder).
2. Magnetic resonance or computerized tomography with major structural alterations.
3. Pregnant or breastfeeding women.
4. Patients with hypersensitivity to ketamine
5. Cardiac insufficiency
6. Patients with a history of psychosis
7. Patients with first-degree relatives with a history of psychosis
8. Patients with uncontrolled glaucoma
9. Current neurological illness