- Risks and benefits: besides the (low) risks of general anaesthesia and a standard laparoscopy, the most important risks associated with participation are (cumulative) locoregional toxicity of intraperitoneal aerosolised oxaliplatin, (cumulative) systemic toxicity of intraperitoneal aerosolised oxaliplatin with simultaneous intravenous bolus 5-fluorouracil/leucovorin, and inefficacy of upfront repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin. However, so far, no severe (cumulative) locoregional toxicity of intraperitoneal aerosolised oxaliplatin has been observed during/after PIPAC. Furthermore, the (cumulative) systemic toxicity of intraperitoneal aerosolised oxaliplatin (92 mg/m2 every 6 weeks) is likely to be lower than the intravenous dose during standard palliative systemic therapy (85-130 mg/m2 every 2-3 weeks). Moreover, the (cumulative) systemic toxicity of intravenous bolus 5-fluorouracil/leucovorin (400/20 mg/m2 every 6 weeks) is likely to be lower than the intravenous dose during standard palliative systemic therapy (2800/400 mg/m2 every 2 weeks). Finally, repeated laparoscopic PIPAC with oxaliplatin has revealed promising preliminary oncological efficacy outcomes in patients with end-stage colorectal peritoneal metastases, while palliative systemic therapy appears relatively uneffective in this setting. Taken together, the investigators feel the benefits of participation outweigh the risks, since upfront repeated laparoscopic PIPAC with oxaliplatin and simultaneous intravenous bolus 5-fluorouracil/leucovorin may result in long-term intraperitoneal disease control with low systemic side-effects and a small chance of secondary curative intent surgery. Thereby, this intervention potentially postpones palliative systemic therapy and increases the quality of life and prognosis of this particular population with an extremely poor prognosis.