The CEA/PCI ratio is a superior prognosticator than mCOREP for colorectal cancer patients with peritoneal carcinomatosis

Background The CEA/PCI ratio, which evaluates tumour marker and burden, has been demonstrated as a prognosticator for patients with colorectal cancer with peritoneal carcinomatosis. The aim of this study was to compare the CEA/PCI ratio with the Modified Colorectal Peritoneal Score (mCOREP) for overall survival (OS) and recurrence free survival (RFS). There is no literature currently comparing both markers for RFS. Methods Data was collected retrospectively for patients undergoing CRS and hyperthermic intraperitoneal chemotherapy (HIPEC) at the Peritonectomy Unit at St. George Hospital, NSW from January 2015 to December 2021. Results From 187 patients, an increase in CEA/PCI ratio was associated with reduced OS (p < 0.01) and RFS (p < 0.01), whereas mCOREP score did not demonstrate such association with OS (p = 0.5) nor RFS (p = 0.4). However, CEA/PCI ratio greater than the median of 0.63 was correlated with an increased OS (p = 0.01), whereas the mCOREP greater than the median of 4 correlated with reduced OS (p < 0.01). Median mCOREP also demonstrated association with reduced RFS in patients with PCI <15 (p = 0.03), whereas CEA/PCI ratio above 0.63 demonstrated association with reduced RFS in patients with PCI ≥ 15 (p = 0.02). Conclusion The CEA/PCI ratio is more associated with OS and RFS in patients with colorectal cancer with peritoneal carcinomatosis, when compared with mCOREP. CEA/PCI ratio above 0.63 was correlated with increased OS, whereas mCOREP above 4 is correlated with reduced OS. CEA/PCI ratio above 0.63 demonstrated reduced RFS for patients with higher PCIs. By contrast, mCOREP >4 illustrated reduced RFS in patients with lower PCIs.