Eligibility Criteria:
Inclusion Criteria:
* Being over 18 years old
* Suffering from advanced cancer
* Having a clinically estimated life expectancy over 3 months.
* Being diagnosed from having a depressive syndrome by a Hospital Anxiety and Depression Scale-D over 11.
* Being in need of an antidepressant treatment.
* Suffering from at least one under-controlled symptom (defined as a score over 3 on the Edmonton Symptom Assessment Scale) among: pain, nausea, vomiting, breathlessness, lack of appetite, sleep disorders, anxiety or impaired wellbeing.
* Having or not a cancer treatment.
* Being able to understand the information related to the study, and to sign informed consent.
* Having agreed to take part to the study.
* Being able to fill Patient Reported Outcomes questionnaires.
* Being available to be call on days 7 and 14.
* Having a social security affiliation.
Exclusion Criteria:
* Being treated by an antidepressive agent during the four weeks before inclusion.
* Having had a hypersensitivity event to mirtazapine, escitalopram of any excipient.
* Having had a prior inefficient treatment by mirtazapine or escitalopram.
* Having postural hypotension or arterial systolic hypotension inferior to 90 mmHg measured following the guidelines of the European Society of Cardiology
* Having a QT interval over 420 ms.
* Having uncontrolled hearth rhythm disorder or uncontrolled conduction disorder.
* Having had or having bipolar disorder.
* Having uncontrolled seizure or epilepsy (relative non-inclusion criteria needing a neurology specialist opinion)
* Having or having history of closed-angle glaucoma.
* Having bone marrow aplasia.
* Practicing breast-feeding or being pregnant.
* Women of childbearing age with no contraception method.
* Having a treatment with:
* Monoamine oxidase inhibitors (Selegiline, Moclobemide, Isocarboxazid, Nialamide, Phenelzine, Tranylcypromine, Iproniazid, Iproclozide, Toloxatone, Linezolid, Safinamide, Rasagiline)
* One of the following antiarrhythmic drugs: Flecainide, Propafenone, any class IA and III antiarrhythmic drug (amiodarone, disopyramide, hydroquinidine, quinidine, procainamide, sparteine, ajmaline, prajmaline, lorajmine, bretylium tosilate, bunaftine, dofetilide, ibutilide, tedisamil, dronedarone).
* Linezolid, sparfloxacin, moxifloxacin, macrolides (IV erythromycin, josamycin, clarithromycin, telithromycin), pentamidin, halofantrine, HIV protease inhibitors (ritonavir, nelfinavir, amprenavir, indinavir), azolic antifungal agents (ketoconazole, itraconazole, miconazole, fluconazole, voriconazole)
* Mizolastine and Astémizole
* St. John's wort
* Having genetic galactose intolerance or glucose-galactose malabsorption.
* Having one of the following electrolyte disorders not corrected at the time of inclusion: hyponatremia, hyperkalemia, hypokalemia, hypermagnesemia, and hypomagnesemia.
* Having end-stage renal disease with a creatinine clearance inferior to 15 ml/min calculated using the Cockroft's formula.
* Having hepatic failure.
* Having legal incapacity