This will be a multicentre study in which 176 eligible patients will be randomized to adjuvant HIPEC followed by adjuvant systemic chemotherapy in the experimental arm, or the standard adjuvant systemic chemotherapy alone in the control arm. Adjuvant HIPEC will be performed preferably simultaneously or within 10 days after resection of the primary tumour, either by laparoscopy or open approach, similar to the technique used for resection of the primary tumour. If adjuvant HIPEC cannot be performed within 10 days (i.e. complicated postoperative course), the procedure will be delayed until 5 to 8 weeks postoperatively. Subsequently, patients will receive routine adjuvant chemotherapy (CAPOX) within 3 weeks from HIPEC. Diagnostic laparoscopy will be performed routinely after 18 months postoperatively in both arms of the study in patients without evidence of disease based on routine follow-up using CT imaging and CEA. If peritoneal carcinomatosis is found during staging laparoscopy, CR/ HIPEC will be performed in patients with a maximum of 5 involved regions and without evidence of systemic disease.