Could chemo around surgery beat cancer spread in the belly?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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 the peritoneal cancer index (PCI) is appropriately scored and documented before enrolment. Patients are excluded in case of any comorbidity or condition that prevents safe administration of the planned perioperative systemic therapy, determined by the treating medical oncologist, e.g.: * Inadequate bone marrow, renal, or liver functions (e.g. haemoglobin \<6.0 mmol/L, neutrophils \<1.5 x 109/L, platelets \<100 x 109/L, serum creatinine \>1.5 x ULN, creatinine clearance \<30 ml/min, bilirubin \>2 x ULN, serum liver transaminases \>5 x ULN); * Previous intolerance of fluoropyrimidines or both oxaliplatin and irinotecan; * Dehydropyrimidine dehydrogenase deficiency; * Serious active infections; * Severe diarrhoea; * Stomatitis or ulceration in the mouth or gastrointestinal tract; * Recent major cardiovascular events; * Unstable or uncompensated respiratory or cardiac disease; * Bleeding diathesis or coagulopathy; * Pregnancy or lactation. The aforementioned laboratory values and tests are to be determined at the discretion of the physician, e.g. only if the patient is suspect for abnormal conditions tests will be conducted.