Cytoreductive Gastrectomy After Systemic Therapy Versus Systemic Therapy Alone For Limited Metastasis Gastric Cancer

Inclusion criteria General criteria

* Age 18-75
* GCLM detected on surgical exploration and demonstrated by histology or cytology
* Localized peritoneal carcinomatosis (P1 or P2 score), according to the classification of the Japanese Research Society for Gastric Cancer
* Liver metastasis lesions of maximum diameter ≤5 cm
* Para-aortic lymph node metastasis below the coeliac axis or above the inferior mesenteric artery (lymph node 16a1/b2 of maximum diameter≥1cm)
* Bilateral or unilateral Krukenberg tumors were allowed and considered 1 incurable organ site
* The accepted patient has two metastases
* Baseline Eastern Cooperative Oncology Group (ECOG) performance status \< 1
* Basic laboratory tests demonstrating adequate bone marrow function (neutrophil count \> 1500mm3, haemoglobin \> 8g/dL, platelet count \> 100,000/mm3), adequate liver function (bilirubin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) within upper limits of normal), adequate renal function (serum creatinine within the upper limit of normal)
* Expected survival \> 3 months
* Able to tolerate enteral nutrition and adequate mental capacity to give informed consent
* Completed 4 cycles of first-line standard-of systemic therapy
* Repeat diagnostic laparoscopy after first-line treatment prior to randomization demonstrating feasible resection.

Eligibility criteria for resection \& extent of proposed resection

* Staging scans (cross-sectional imaging) demonstrating no extra metastases (lung, bone,...)
* Cross-sectional imaging demonstrating no local progression of PM
* PCI score \<12
* Cytology +ve alone (no gross PM) permissible for enrolment
* Feasible R0 resection (reasonable chance of negative margins on histology)
* Feasible D1, D1+ or D2 lymphadenectomy

Exclusion criteria

* Any extra-abdominal metastasis at diagnosis or during systemic treatment.
* Past history of malignancy other than gastric cancer diagnosed in the last 5 years except for basal cell carcinoma of skin or preinvasive cancer of cervix
* Patients in the reproductive age who declined to use an adequate means of contraception
* Significant disease or conditions which, in the investigator's opinion, would exclude patient from the study
* Uncontrolled concurrent illness including but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia
* Psychiatric illness/social situations that would limit compliance with study requirements
* Pregnant and lactating females
* Prior surgical treatment for GC involving resection
* Clinical or radiological progression during 1st line systemic treatment

  * Patients with radiological progression of LM (determined by RECIST criteria) to be excluded as disease is likely not responding well to 1st line treatment.
  * Patients with clinical progression of LM as defined by increasing ascites requiring intervention (ascitic tap/drain, hospital admission etc) or causing significant symptoms to the patient (tense distended abdomen, early satiety, shortness of breath etc).

    * Ascites volume as a reflection of disease control is difficult to assess and quantify or a reflection of disease progression. (15)
* Any patient deemed unresectable or requiring extensive resection beyond procedure approved in the study protocol

  * PCI \> 12
  * Extensive bowel / mesentery involvement requiring \>2 separate / non-contiguous small or large bowel resections in addition to the gastrectomy
  * Involvement of the head of pancreas or bile duct
  * PM or nodal disease in the hepatoduodenal ligament
  * Involvement of major vascular structures
  * Involvement of esophagus precluding a reasonable chance of R0 resection by transhiatal approach Withdrawal Criteria
* Patient decides to withdraw from the study, or
* The investigator concludes that it is in the patient's best interest to discontinue study treatment.