Aims: Selecting patients for cytoreductive surgery and hyperthermic intra-peritoneal chemotherapy (HIPEC) remains challenging. We compared the predictive power of three intra-operative assessment tools of peritoneal involvement of colorectal cancer.
Methods: Ninety-two procedures (1999-2005) were prospectively scored using the Simplified Peritoneal Cancer Index (SPCI) and 7 Region Count. The Peritoneal Cancer Index (PCI) was retrospectively scored using the SPCI tool, operative notes and pathological reports. Endpoints were completeness of cytoreduction and overall survival. Logistic regression and Receiver Operating Characteristic (ROC) curves were applied to compare the predictive value of the three scoring systems on completeness of cytoreduction.
Results: After a median follow-up of 31 months, the median overall survival was 25.6 months. It decreased to 7.3 months, when cytoreduction was incomplete (p=0.001). An increased PCI, SPCI or number of regions were all associated with a decrease in probability of complete cytoreduction (p<0.05). With complete cytoreduction as outcome, the ROC areas for the PCI, SPCI and 7 Region Count were 0.92, 0.94 and 0.90, respectively (p=0.14). Using a cut-off value of 16 in the PCI system (p=0.03), 13 in the SPCI system (p=0.04) and 6 regions in the 7 Region Count (p=0.0002) the probability of complete cytoreduction decreased significantly.
Conclusion: The PCI, SPCI and 7 Region Count are useful and equally effective prognostic tools predicting completeness of cytoreduction and associated improved survival. The 7 Region Count may be preferred due to its practical simplicity.