Development and Validation of a Nomogram for Predicting Overall Survival In Synchronous Peritoneal Metastasis of Colorectal Cance

Abstract Background: Synchronous peritoneal metastases (PM) is a difficult issue to tackle and the prognosis is poor. The aim of this study is to construct a nomogram to predict the overall survival (OS) for synchronous colorectal peritoneal metastasis.Method: In this retrospective study, 332 patients with synchronous PM were included. The training cohort consisting of 251 patients underwent abdominal surgery from February 2007 to February 2018. The risk factors related to prognosis were analyzed by Kaplan-Meier curve and Cox regression model. 81 patients from other two hospitals were enrolled as validation cohort. The prediction effect of this nomogram was evaluated by C-index and the calibration curve. Result: Five predictors were enrolled into this nomogram after multivariate analysis, including age, peritoneal cancer index (PCI), completeness of cytoreductive surgery (CRS), CA19-9, and albumin. The nomogram showed the accuracy to predict the OS at 0.5, 1, 2, and 3 years. The C-index of the nomogram in the training cohort and validation cohort were 0.713 (95% CI, 0.674–0.752) and 0.642 (95% CI, 0.563-0.720) separately. Both training and validation cohorts showed good discrimination of the nomogram for OS. Calibration curves have shown the predicted OS of nomogram are consistent with actual survival.Conclusion: This novel nomogram, combined with age, PCI, CRS, CA19-9, and albumin, has shown good accuracy to predict OS in patients with synchronous PM, which could be used as an easy-to-use tool for clinicians and surgeons to make decisions.