Individualized Intraperitoneal and System Chemotherapy Versus System Chemotherapy as First-line Chemotherapy for AGC

Inclusion Criteria:

* Patients must have histologically confirmed adenocarcinoma of the stomach or gastro-oesophageal junction with inoperable locally advanced or metastatic disease, not amenable to curative therapy.
* Patients must have measurable disease, according to the Response Evaluation Criteria in Solid Tumors (RECIST, v1.1), assessed using imaging techniques (CT or MRI).
* Patients must have enough tumor tissue for mRNA expression test.
* Women of childbearing potential must be non-pregnant (negative pregnancy test within 72 hours prior to chemotherapy, postmenopausal woman must have been amenorrheic for at least 12 months to be considered of non-childbearing potential) and nonlactating, and men and women must be willing to exercise an effective form of birth control (abstinence/contraception) while on study and for 6 months after therapy completed
* Eastern Cooperative Oncology Group (ECOG) Performance status 0, 1 or 2.
* Absolute neutrophil count (ANC) \>=1,500/ul
* Platelets (PLT) \>=75,000/ul
* Serum bilirubin \<= 1.5 × upper limit of normal (ULN)
* Aspartate transaminase (AST) or alanine aminotransferase (ALT) \<= 2.5 × ULN (or \<= 5 × ULN in patients with liver metastases)
* Alkaline phosphatase \<= 2.5 × ULN (or \<= 5 × ULN in patients with liver metastases, or \<= 10 × ULN in patients with bone but no liver metastases)
* Albumin \>= 25 g/L.
* Creatinine clearance \>= 60 mL/min.
* Life expectancy of at least 3 months.
* Signed informed consent.

Exclusion Criteria:

* Previous chemotherapy for advanced/metastatic disease (prior adjuvant/neoadjuvant therapy is allowed if at least 6 months has elapsed between completion of adjuvant/neoadjuvant therapy and enrolment into the study; the total dose of cisplatin should be less than 300mg/m\^2).
* Patients with active (significant or uncontrolled) gastrointestinal bleeding.
* Residual relevant toxicity resulting from previous therapy (with the exception of alopecia), e.g. neurological toxicity ≥ grade 2 NCI-CTCAE 4.0.
* Other malignancy within the last 5 years, except for carcinoma in situ of the cervix, or basal cell carcinoma.
* History of documented congestive heart failure; angina pectoris requiring medication;evidence of transmural myocardial infarction on ECG; poorly controlled hypertension (systolic BP \> 180 mmHg or diastolic BP \> 100 mmHg); clinically significant valvular heart disease; or high risk uncontrollable arrhythmias.
* Baseline left ventricular ejection fraction (LVEF) \< 50% (measured by echocardiography or MUGA).
* Patients with dyspnoea at rest due to complications of advanced malignancy or other disease, or who require supportive oxygen therapy.
* Patients receiving chronic or high dose corticosteroid therapy. (Inhaled steroids and short courses of oral steroids for anti-emesis or as an appetite stimulant are allowed).
* Clinically significant hearing abnormality.
* Known dihydropyrimidine dehydrogenase (DPD) deficiency.
* History or clinical evidence of brain metastases.
* Serious uncontrolled systemic intercurrent illness, e.g. infections or poorly controlled diabetes.
* Positive serum pregnancy test in women of childbearing potential.
* Received any investigational drug treatment within 4 weeks of start of study treatment.
* Radiotherapy within 4 weeks of start of study treatment (2 week interval allowed if palliative radiotherapy given to bone metastatic site peripherally and patient recovered from any acute toxicity;prior adjuvant radiotherapy is allowed if complete at least 6 months ).
* Major surgery within 4 weeks of start of study treatment, without complete recovery.
* Patients with known active infection with HIV, hepatitis B virus (HBV), or hepatitis C virus (HCV).
* Known hypersensitivity to any of the study drugs.