Patients with metastatic adenocarcinoma of the stomach or the esophagogastric junction (II-III type by Siewert) without previous therapy will be treated with one of two chemotherapy combinations . One half of the patients gets 5-Fluorouracil (5-FU), Leucovorin, Oxaliplatin (FOLFOX6), the others 5-Fluorouracil (5-FU), Leucovorin, Oxaliplatin and Irinotecan (mFOLFIRINOX). Main objective of the study is progression free survival.

This parallel, randomized, open-label study 326 patients with metastatic ( adenocarcinoma of the stomach or the esophagogastric junction without previous therapy will be included in this study. After randomization patients receive 9 cycles FOLFOX6 or mFOLFIRINOX.

Stratification factors include ECOG, site of metastasis, age, pathological subtypes.

Efficacy will be evaluated every 3 cycles with RECIST. Toxicity will be assessed with WHO CTC 3.0 every 2 weeks.

Inclusion Criteria:

1. histologically confirmed locally advanced, recurrent or metastatic adenocarcinoma of the esophagogastric junction (Siewert type II-III) or the stomach
2. no prior palliative chemotherapy or radiation therapy
3. Age 18-70 years (female and male)
4. Eastern Cooperative Oncology Group ≤ 2
5. Neutrophils> 2.000/µl
6. Platelets > 100.000/µl
7. Normal value of Serum Creatinin
8. Albumin level > 29 г/л
9. Aspartate transaminase (AST) or alanine transaminase (ALT) less than 3 times the upper limits of normal (ULN)
10. Total Bilirubin less than 1.5 times the ULN
11. Written informed consent.

Exclusion Criteria:

1. Previous palliative cytostatic chemotherapy
2. Cancer relapse
3. Complicated gastric cancer (perforation, bleeding, sub or decompensated stenosis, dysphagia IV)
4. Diarrhea ≥ 2 according to the criteria of Common Terminology Criteria for Adverse Events (CTCAE) version 4.1;
5. Hypersensitivity against 5- Fluorouracil, Leucovorin, Oxaliplatin, irinotecan
6. Existence of contraindications against 5- Fluorouracil, Leucovorin, Oxaliplatin, Irinotecan or Docetaxel
7. Active coronary heart disease, Cardiomyopathy or cardiac insufficiency stage III-IV according to New York Heart Association (NYHA)
8. Severe non-surgical accompanying disease or acute infection (uncontrolled arterial hypertension, diabetes mellitus, stroke less than 6 months old, mental disorders, other tumors and others)
9. Malignant secondary disease, dated back < 5 years (exception: In-situ-carcinoma of the cervix uteri, adequately treated skin basal cell carcinoma)
10. Peripheral polyneuropathy > Grad II
11. Liver dysfunction (AST)/ALT>3,0xULN, ALT>3xULN, Bilirubin>1,5xULN) Serum Creatinin >1,0xULN
12. Chronic inflammable gastro-intestinal disease
13. Inclusion in another clinical trial
14. Pregnancy or lactation
15. Hepatitis B or C in the active stage
16. Human immunodeficiency virus(HIV) infected
17. Serious concomitant somatic and mental illnesses / deviations or territorial causes that may prevent the patient from participating in the protocol and observing the protocol schedule
18. Foreigners or persons with limited legal status