Perioperative Systemic Therapy for Isolated Resectable Colorectal Peritoneal Metastases

Eligible patients are adults who have: * a World Health Organisation (WHO) performance status of ≤1; * histological or cytological proof of PM of a non-appendiceal colorectal adenocarcinoma with ≤50% of the tumour cells being signet ring cells; * resectable disease determined by a diagnostic laparoscopy/laparotomy in combination with abdominal computed tomography and/or magnetic resonance imaging (MRI); only in patients in whom diagnostic laparoscopy or laparotomy is considered not feasible or valuable (e.g. due to known adhesions impeding adequate PCI scoring), it is also allowed to determine resectability by CT or MRI only (provided that the colorectal PM are histologically or cytologically proven); * no evidence of systemic colorectal metastases within three months prior to enrolment; * no systemic therapy for colorectal cancer within six months prior to enrolment; * no contraindications for CRS-HIPEC; * no previous CRS-HIPEC; * no concurrent malignancies that interfere with the planned study treatment or the prognosis of resected colorectal PM. Importantly, enrolment is allowed for patients with radiologically non-measurable disease. Enrolment is also allowed for patients who are referred to a study centre after a macroscopically complete resection of colorectal PM in a referring centre, since it is assumed that microscopic (and often macroscopic) colorectal PM are still present. The diagnostic laparoscopy/laparotomy may be performed in a referring centre, provided that…