Dedicated MR Imaging vs Surgical Staging of Peritoneal Carcinomatosis in Colorectal Cancer

HYPOTHESIS Staging with dedicated MRI will lead to a reduction of staging laparoscopies and explorative laparotomies in colorectal patients with PM to evaluate whether they may benefit from CRS-HIPEC OBJECTIVES The goal is to perform a multicenter randomized study to compare a less invasive diagnostic workup ARM A (with MRI and surgical inspection reserved for borderline operable cases on MRI) to the standard diagnostic workup (ARM B, without MRI, with surgical staging to determine resectability based on a MDT decision) of patients with (suspected) peritoneal metastases. Surgical staging laparoscopies may largely be replaced by MRI (only reserved as a problem solver for borderline operable cases in ARM A). If it will be proven that MRI is an accurate, robust and cost-effective staging tool than this will result in a more patient friendly diagnostic workup with less futile surgical procedures. STUDY DESIGN 4-year multicenter randomized controlled trial STUDY POPULATION N=272 patients suspected of synchronous or metachronous peritoneal metastases of colorectal origin who are considered for CRS-HIPEC after CT imaging. EXPERIMENTAL (ARM A) CRS-HIPEC candidates are selected based on MRI and only in borderline cases a surgical inspection will be performed CONTROL (ARM B) Standard work-up including computed tomography and surgical inspection as appropriate (based on a MDT decision). MAIN STUDY PARAMETERS/ENDPOINTS Primary outcome: Number of preventable unnecessary laparoscopies and explorative laparotomies. NATURE AND EXTENT OF THE BURDEN AND RISKS ASSOCIATED WITH PARTICIPATION, BENEFIT AND GROUP RELATEDNESS: MRI is a standard diagnostic procedure without the use of radiation. The MR sequences, MR-contrast agents and Buscopan (to minimize peristaltic bowel movements) are all commonly used in daily clinical practice. In addition, patients will be asked to drink 1L of pineapple juice 1-2 hours before the MRI (to minimize signal in the bowel lumen and optimize image quality), which is standard procedure in many clinics for MRCP and MR enterography. By acting upon the MRI findings in the experimental arm A, could result into new risks as oppose to standard clinical practice. However by introducing the borderline group ('yellow light' group) to receive diagnostic laparoscopy will minimize the possibility of over-staging a patient that would have received a successful CRS/HIPEC in de control arm. In our internal pilot data of 87 patients considered for CRS/HIPEC, no patients with a PCI of above 24 ended up receiving successful CRS/HIPEC and only 4 of the 15 patients that could have been assigned to the borderline group (were the trail to have run at that time) received successful CRS/HIPEC.