Efficacy and Safety of Trastuzumab, Capecitabine y Oxaliplatine as Treatment Gastric Cancer Metastatic (HER2)Positive

Inclusion Criteria:

* Patients be able to grant a written informed consent or oral consent
* Age ≥18 years old
* Patients diagnosed with metastatic gastric or gastro-esophageal junction adenocarcinoma (HER2-positive), unresectable and histologically confirmed Measurable disease, following the new RECIST criteria,
* HER2 positive tumors (primary or metastatic) with overexpression HER2 determinated by IHQ +++ (IHQ3+) o IHQ ++ confirmed by FISH/SISH positive (IHQ2+/FISH+)
* ECOG ≤ 2
* Patients of childbearing potential (\< 12 months from last menstruation), they have to use effective means of contraception
* Life expectancy more than 3 months
* Adequate renal function: calculated creatinine clearance \> 50 mL/min
* Adequate liver function: AST and ALT ≤2.5 x LSN (5 x LSN with liver metastasis), bilirubin 1,5 x LSN. alkaline phosphatase \< 2,5 x LSN (≤ 5 x LSN with liver metastasis o \< 10 x LSN with bone metastases Adequate haematological function: Hb ≥9 g/dl, neutrophils ≥ 1,5 x 109 /l and platelets 100 x 109 /l.
* Normal Left Ventricle Fraction Ejection , LVEF\> 50%
* Every patient should be treated and followed in his / her study site

Exclusion Criteria:

* Prior chemotherapy treatment for advanced/metastatic disease
* Lack of physical integrity of the upper gastrointestinal tract or malabsorption
* Patients with active gastrointestinal bleeding
* Prior chemotherapeutic treatment for advanced / metastatic disease
* Toxicity as a result of prior therapy (except alopecia)., for example.
* Neurology toxicity grade ≥2NCI-CTCAE
* Patients who received radiotherapy within 4 weeks prior to study treatment.
* Major surgical procedures within 4 weeks prior to treatment without a total surgical recovery.
* Past or current history of other malignancies (within the last 5-2 years prior to treatment start), patients with curatively treated basal cell carcinoma of the skin or in situ carcinoma of the cervix are eligible
* Active and clinically significant cardiovascular disease,
* History or current clinical evidence of brain metastasis
* Patients undergoing transplantation allogenic requiring immunosuppressive treatment
* Moderate or severe renal failure, creatinine clearance \< 50 mL/min, calculated by Cockcroft-Gault
* Adequate liver function: bilirubin ≤1.5 x UL, GOT ( ASAT )/ GPT ( ALAT ) ≤2,5 LSN. Liver metastasis ≤ 5 x LSN, FA ≤ de 2,5 feces el LSN.
* Adequate haematology function: neutrophils ≥ 1,5 x 109 /l and platelets 100 x 109 /l
* Treatment with sorivudine and the analogous as brivudine.
* Dihydropyrimidine proven dehydrogenase deficiency (DPD).
* Patients who had received any drug, agent or investigational procedure, or who have participated in another research study within 30 days prior to initiation of treatment with study medication.
* Hypersensitivity to any of the study drugs
* Evidence of any other disease, metabolic dysfunction, physical examination finding or laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or puts the patient at high risk for treatment-related complications
* Patients receiving chronic corticosteroid therapy or high dose (is allowed to use inhaled steroids and cycle short treatment with oral steroids for prevention of emesis or to stimulate appetite)
* Pregnancy and lactation
* Patients of childbearing potential not willing to use effective means of contraception.
* History of psychiatric disorders that the investigator considered clinically significant, causing the patient give informed consent or interfere with compliance with study procedures.