Development of a prognostic model for postoperative survival in appendiceal pseudomyxoma peritonei based on clinical indicators.

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare peritoneal malignancy primarily originating from appendiceal mucinous neoplasms. Prognosis is influenced by histologic subtype, tumor markers, and the completeness of cytoreduction. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is the standard treatment. This study aims to identify key factors affecting long-term prognosis in appendiceal PMP patients and develop a dynamic nomogram for postoperative survival prediction.

METHODS

This study retrospectively analyzed the clinical data of 153 patients with appendiceal-origin PMP confirmed by postoperative pathology from Jinan Central Hospital between October 2017 and December 2024. The primary endpoint was postoperative overall survival (OS). Patients were randomly divided into modeling (107 cases) and validation (46 cases) groups. Nonlinear relationships between continuous variables and survival time were assessed using restricted cubic splines (RCS) and ANOVA. Univariate Cox regression identified risk factors for postoperative OS, while Lasso regression generated a new variable, the LASSO-derived inflammation-nutrition score (LINS), from selected hematological indices. Multivariate Cox regression analysis identified independent prognostic factors, including histological type, preoperative peritoneal cancer index (PCI), CA125, LINS, and Completeness of Cytoreduction (CC) score (P < 0.05). A nomogram was developed to predict 1-, 3-, and 5-year postoperative OS. Model performance was validated using time-dependent ROC curves and calibration curves. Additionally, a dynamic nomogram was created using the Shiny application framework to predict survival probabilities in real-time.

RESULTS

The 1-, 3-, and 5-year survival rates for the 153 patients were 82.54%, 66.00%, and 56.76%, respectively. The multivariate Cox regression identified LINS, CA125, preoperative PCI, histological type, and CC score as independent prognostic factors (P < 0.05). The nomogram demonstrated good predictive ability, with time-dependent ROC AUC values for the modeling group of 0.945, 0.823, and 0.736 at 1, 3, and 5 years. Calibration curves showed good agreement between predicted and observed survival. A dynamic survival prediction tool was developed and is accessible via a Shiny app ( https://lq1999.shinyapps.io/Dynamic/ ).

CONCLUSION

Histological type, preoperative PCI, CA125, LINS, and CC score are independent prognostic factors in appendiceal PMP. The developed nomogram offers accurate survival predictions and can be updated with new data for improved clinical decision-making.