Inclusion Criteria:

• Restricted to 18 to 80 years of age.
• ECOG performance status ≤ 2.
• Histologic confirmation of gastric adenocarcinoma including all subtypes and Siewert type III GE junction adenocarcinomas
• Adequate renal, and bone marrow function:
  • Leukocytes ≥ 3,000/uL;
  • Absolute neutrophil count ≥ 1,500/uL;
  • Platelets ≥ 50,000/Ul d. Serum creatinine ≤ 1.5 mg/dL.
• Metastasis confined to the peritoneum:
  • Positive peritoneal cytology;
  • Peritoneal metastasis on diagnostic laparoscopy;
  • Peritoneal metastasis on imaging.
• Response to systemic chemotherapy defined as at least one of the following:
  • Reduction (≥ 30%) in SUV max;
  • Reduction in size of primary tumor, regional lymph node or peritoneal metastasis on imaging (≥ 30% decrease in the longest diameter of target lesion) or laparoscopy (reduction in PCI or conversion of peritoneal cytology);
  • Reduction (≥ 30%) in serum tumor markers CEA or CA 19-9.
• Peritoneal Carcinomatosis Index (PCI) ≤ 7 and surgeon deems high likelihood for a complete cytoreduction.
• BMI ≤ 35 kg/m^2.

Exclusion Criteria:

• Distant metastatic disease not limited to peritoneum, such as solid organ metastases (liver, lung, bone, distant lymph node, etc).
• Malignant ascites at time of study enrollment.
• Comorbidities that would preclude protocol therapy.
• Women with a positive urine or serum pregnancy test are excluded from this study; women of childbearing potential (defined as those who have not undergone a hysterectomy or who have not been postmenopausal for at least 24 consecutive months) must agree to refrain from breast feeding and practice adequate contraception as specified in the informed consent. Adequate contraception consists of oral contraceptive, implantable contraceptives, injectable contraceptives, a double barrier method, or abstinence.
• Subjects deemed unable to comply with study and/or follow-up procedures.
• Subjects with a known hypersensitivity to protocol systemic chemotherapy that was lifethreatening, required hospitalization or prolongation of existing hospitalization, or resulted in persistent or significant disability or incapacity.