- Secondary objectives: to determine the environmental safety of laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the pharmacokinetics of oxaliplatin in plasma, urine, and saliva of the patient after (repeated) laparoscopic PIPAC with oxaliplatin; to determine intraoperative characteristics of (repeated) laparoscopic PIPAC with oxaliplatin; to determine the hospital stay after (repeated) laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the readmission rate after (repeated) laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the number of interventions in each patient; to determine the organ functions during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the histological tumour response during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the macroscopic intraperitoneal tumour response during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine tumour markers during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the peritoneal progression-free survival during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the systemic progression-free survival during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the disease-specific survival during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the overall survival during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the quality of life during repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to determine the costs of repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin; to collect tissue samples, ascites, and blood samples for translational research purposes. See section 'Outcome measures' below for detailed information on the secondary and other outcome measure belonging to these secondary objectives.