Inclusion Criteria:

- 18 < age ≤ 75 years old

- White blood cells > 3,500/mm3, neutrophils ≥ 1,500/mm3, platelets ≥ 100,000/mm3

- Good renal functions, serum creatinine values being < 1.5 mg/dl and creatinine
clearance > 60 ml/min

- Performance Status ≤1, Karnofsky Index ≥ 70%

- Serum bilirubin ≤ 2 mg/dl

- Having given written informed consent prior to any procedure related to the study.

- Covered by a Health System where applicable, and/or in compliance with the
recommendations of the national laws in force relating to biomedical research

- Not under any administrative or legal supervision

- Histologically evidenced resectable T3 or T4 gastric adenocarcinoma for which a
curative gastrectomy is scheduled, with invasion into the serosa AND/OR lymph node
metastasis (determined from data obtained by endoscopic ultrasound and chest, abdomen
and pelvis CT scan) AND/OR positive peritoneal cytology (sampled during the
preoperative laparoscopy).

AND/OR

- Perforated gastric adenocarcinoma AND/OR

- Siewert III adenocarcinoma of the cardia for which a gastrectomy by exclusive
abdominal laparotomy is scheduled

- Females of childbearing age potential and male subjects with partners of childbearing
potential using efficient contraceptive measures (as judged by the
investigator).Subjects randomised in the arm with HIPEC should be informed and accept
that these requirements should also extend to :

- 4 months after the treatment with Oxaliplatin for female subjects,

- 6 months after the treatment with Oxaliplatin for male subjects.

Exclusion Criteria:

- Prior malignant tumors with detectable signs of recurrence

- Gastric stump adenocarcinoma

- Presence of comorbidities, notably serious chronic diseases or organ failure General
conditions

- Any subject in exclusion period of a previous study according to applicable
regulations

- Pregnancy or breastfeeding

- Females of childbearing age potential or male subjects with partners of childbearing
potential not using medically accepted contraceptive measures, as judged by the
investigator Interfering substance

- Contraindication to any drug contained in the chemotherapy regimen Specific to the
study

- Life threatening toxicity before surgery

- Distant metastases (liver, lung. ovaries, etc)

- Tumoral infiltration of the head or body of the pancreas

- Patients presenting an adenocarcinoma of the cardia Siewert I or II

- Existence of macroscopic peritoneal implants

- Patients with clinically significant ascites (> 500 cc) even if cytology is negative
for cancer cells, in the absence of other non-malignant causes of ascites