Prognostic Relevance of the Peritoneal Surface Disease Severity Score Compared to the Peritoneal Cancer Index for Colorectal Peritoneal Carcinomatosis

Background. Peritoneal Carcinomatosis Index (PCI) is a widely established scoring system that describes disease burden in isolated colorectal peritoneal carcinomatosis (CPC). Its significance may be diminished with complete cytoreduction. We explore the utility of the recently described Peritoneal Surface Disease Severity Score (PSDSS) and compare its prognostic value against PCI. Methods. The endpoints were overall survival (OS), progression-free survival (PFS), and survival less than 18 months (18 MS). Results. Fifty patients underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) for CPC from 2003 to 2014, with 98% achieving complete cytoreduction. Median OS was 28.8 months (95% CI, 18.0–39.1); median PFS was 9.4 months (95% CI, 7.7–13.9). Univariate analysis showed that higher PCI was significantly associated with poorer OS (HR 1.11; 95% CI, 1.03–1.20) and PFS (HR 1.09; 95% CI, 1.03–1.14). Conversely, PSDSS was not associated with either endpoint. Multivariate analysis showed that PCI, but not PSDSS, was predictive of OS and PFS. PCI was also able to discriminate survival outcomes better than PSDSS for both OS and PFS. There was no association between 18 MS and either score. Conclusion. PCI is superior to PSDSS in predicting OS and PFS and remains the prognostic score of choice in CPC patients undergoing CRS/HIPEC.