The majority of patients with upper gastrointestinal cancer, such as gastric, biliary, or pancreatic carcinoma, present with metastatic disease, and have an extremely poor survival, irrespective the type of treatment modality. The aim of the current monocentric phase II study is to evaluate in these patients the effectiveness of cytoreductive surgery (CRS) plus hyperthermic intraoperative peritoneal chemotherapy with cisplatin (HIPC). The study is designed to have at least 80% power to detect a 40% increase in 1-year overall survival common to all strata (gastric-biliary-pancreas) after CRS+HIPC. Over an anticipated period of 2 years, 60 patients will undergo CRS + HIPC. Translational research will quantify perioperative circulating and peritoneal tumour cells, based on real-time RT-PCR for CEA and EpCAM. Plasma concentration of cytokines will be determined for IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, IL-13, IFN-γ, and VEGF at several time-points. Systemic immunological changes will be assessed by flow cytometric quantification of the relative proportions and absolute numbers of B- and T-lymphocytes, NK cells, effector T cells, HLA-DR+ T cells, and regulatory T cells. Gene-expression studies will be performed using Affymetrix HG U133 Plus 2.0 arrays on primary and metastatic tissue samples.