Response Prediction of Hyperthermic Intraperitoneal Chemotherapy in gastro-intestinal Cancer (Hi-STEP1)

Interventions: Group 1: During primary curative surgery for gastric or colon carcinoma with synchronous or metachronous peritoneal carcinomatosis, the peritoneal carcinomatosis index (PCI) is determined and biopsies of the PC foci are taken before resection. Surgery is performed according to standard and includes both resection of the primarius and any metastases present and (as far as possible) complete cytoreductive surgery (CCS 0-1) by peritonectomy of the affected sites, followed by HIPEC according to the respective hospital standard. After 6 months, a planned re-operation (laparoscopy/laparotomy) may be performed, depending on the local standard at the respective study center. If a macroscopic PC recurrence is detected, the PCI will be recalculated and a new (as far as possible) complete cytoreductive surgery (CCS 0-1) will be performed by peritonectomy of the affected sites followed by HIPEC according to the respective hospital standard.
The aim of this pilot study is to generate patient-derived tumor organoid models as well as orthotopic mouse models from peritoneal carcinomatosis lesions and to investigate their response to different therapies. Based on the findings of the pilot study, a main clinical trial will then be designed.
Aims of the study are:
1. to describe individualized HIPEC regimens in vitro based on organoid response to therapy and next generation sequencing (NGS) data.
2. the evaluation of individualized HIPEC regimens in vivo in an orthotopic mouse model.
3. the collection of the oncological courses of the patients in the context of the standard tumor follow-up and comparison with the models.
Primary outcome(s): The primary endpoint is to analyze the predictive accuracy of patient-generated tumor organoids (PDOs) for predicting response to HIPEC treatment in patients with peritoneal carcinomatosis (PC).
Study Design: Allocation: ; Masking: ; Control: ; Assignment: ; Study design purpose: treatment