The Peritoneal Cancer Index as a Predictor of Cytoreductive Surgery Outcomes and Heatmapping of Ovarian Cancer Distribution: A Retrospective Analysis

Objective: This study aimed to evaluate the association between the Peritoneal Cancer Index (PCI) and the completeness of cytoreductive surgery (CRS) in patients undergoing surgery for advanced ovarian cancer (AOC). Secondary objectives included identifying a PCI cut-off predictive of incomplete cytoreduction, assessing the relationship between PCI and surgical complexity via the Aletti Surgical Complexity Score (SCS), and exploring disease distribution to better understand ovarian cancer distribution. Methods: A retrospective review of 227 patients undergoing primary or interval debulking surgery for AOC from January 2017 to September 2024 at University Hospitals of Derby and Burton was conducted. PCI was recorded intra-operatively, and procedures were classified using the SCS. ROC analysis identified PCI thresholds for incomplete CRS, logistic regression predicted CRS outcomes, and heat mapping visualised disease distribution. Results: Complete CRS of visible disease (R0) was achieved in 90.75% of patients, while 9.25% had incomplete CRS. Median PCI was significantly higher in incomplete CRS cases (28, IQR 21–32) compared to complete CRS (15, IQR 8–23, p < 0.001). ROC analysis identified a PCI threshold of 25.5 with 71.4% sensitivity and 83.5% specificity for predicting incomplete CRS. PCI > 25.5 increased the odds of incomplete cytoreduction by 12.65 times (p < 0.001). Higher PCI scores correlated with increased surgical complexity, operative time, and blood loss, though complication rates were similar. Heat maps showed stepwise disease distribution from pelvis to upper abdomen. Conclusions: PCI is a reliable predictor of CRS completeness in AOC, with a threshold of >25.5 indicating a high risk of incomplete cytoreduction. The study underscores PCI’s role in surgical planning and calls for multi-centre studies to validate these findings and further examine disease distribution.