The study investigates the outcomes of hyperthermic intraperitoneal chemoperfusion (HIPEC) in combination with curative-intent gastrectomy in resectable locally-advanced and limited-metastatic (low peritoneal cancer index) gastric cancer.

Several recent studies showed that near-perfect curative-intent R0 surgical technique combined with systemic chemotherapy or even immunotherapy may not always be enough to eliminate microscopic deposits or eliminate peritoneal dissemination in locally advanced gastric cancer or low peritoneal cancer-index (PCI) tumors. The risk of peritoneal dissemination is especially high for T4 tumors, for those with cytologically positive peritoneal washings. Moreover, the risk of peritoneal relapse in low PCI tumors is remarkably high. Combination of surgery and intraperitoneal chemotherapy aims to minimise the risks of the aforementioned peritoneal progression. In the study investigators perform curative surgery followed by single dose of hyperthermic intraperitoneal chemotherapy (HIPEC).

Inclusion Criteria:

1. Age 18-80
2. Hystologicaly proven gastric adenocarcinoma
3. ECOG status 0-1
4. Written consent to participate in the study
5. Medically and technically operable gastric tumor
6. Only T4a or T4b tumours with any peritoneal cytology status
7. Cytologically positive peritoneal washings (cyt+) with any T and N criteria
8. Adequate haemopoetic, renal and hepatic function (Hb > 120, PLT > 150*10^9/l, ALT < 60, AST <40, total bilirubin < 21 µmol/l, Creatinine clearance (male - 90-140, female - 80-130 ml/min)

Exclusion Criteria:

1. Pregnancy/breastfeeding
2. ECOG status 2-4
3. Concomitant malignancy
4. Mitomycin and/or Cisplatin hypersensitivity
5. Uncontrollable chronic diseases
6. Patients with coexisting malignancy other than basal cell carcinoma of the skin within the last five years.
7. Presence of metastases other than regional or peritoneal (such as liver, lungs, bone, brain, distant lymph nodes)
8. History of allergic reactions associated with cisplatin and Mitomycin C
9. Patients with psychiatric illness/social situations with impaired compliance
10. •Refusal to participate

The study population will consist of adult patients receiving care at oncological centers in Ukraine who meet all predefined eligibility criteria for this study. Investigators include individuals with for which Gastrectomy+HIPEC is considered an accepted or potentially beneficial treatment option according to national and international clinical guidelines. Participants will be recruited from tertiary surgical oncology hospitals and specialized cancer institutes across Ukraine.