Objective: The aim of this study was to determine whether the extent of peritoneal metastases (PMs) on preoperative diffusion-weighted magnetic resonance imaging (DW-MRI) can be used as a biomarker of disease-free and overall survival in patients with colorectal cancer who are considered for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC).
Methods: For this retrospective cohort study, patients with PMs considered for CRS/HIPEC who underwent DW-MRI for preoperative staging in 2016-2017 were included. The DW-MRI protocol consisted of diffusion-weighted, T2-weighted, and pre- and post-gadolinium T1-weighted imaging of the chest, abdomen, and pelvis. DW-MRI images were evaluated by two independent readers to determine the extent of PMs represented by the Peritoneal Cancer Index (MRI-PCI), as well as extraperitoneal metastases. Cox regression and Kaplan-Meier analysis was performed to determine the prognostic value of DW-MRI for overall and disease-free survival.
Results: Seventy-eight patients were included. CRS/HIPEC was planned for 53 patients and completed in 50 patients (60.5%). Median follow-up after DW-MRI was 23 months (interquartile range 13-24). The MRI-PCI of both readers showed prognostic value for overall survival, independently of whether R1 resection was achieved (hazard ratio [HR] 1.06-1.08; p < 0.05). For the patients who received successful CRS/HIPEC, the MRI-PCI also showed independent prognostic value for disease-free survival for both readers (HR 1.09-1.10; p < 0.05).
Conclusion: The extent of PMs on preoperative DW-MRI is an independent predictor of overall and disease-free survival and should therefore be considered as a non-invasive prognostic biomarker.