Validation of Nomograms Predicting Survival in Patients Undergoing CRS-HIPEC for Peritoneal Dissemination of Mucinous Appendiceal Cancer

BackgroundMucinous appendiceal neoplasms can develop peritoneal metastases, also known as pseudomyxoma peritonei (PMP), which is best treated with cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC).Nomograms can be used to predict the outcomes of patients with PMP of appendiceal origin undergoing CRS-HIPEC.This study aimed to externally validate two (UK and Spanish) existing nomograms using patients from two large-volume centers in the United States. MethodsA prospectively maintained database of peritoneal surface malignancies was used for data collection with additional retrospective review of the electronic health record for missing data.Variables included those used in the nomograms.Receiver operating characteristic (ROC) curves and area under the curve (AUC) values were used to analyze overall survival (OS) and diseasefree survival (DFS). ResultsThe study included 518 patients who underwent CRS-HIPEC from 2007-2024 with peritoneal histology of acellular mucin, low-grade mucinous carcinoma peritonei (LG), high-grade mucinous carcinoma peritonei, and high-grade mucinous carcinoma peritonei with signet ring cells (HG).The AUC ranged from 0.818-0.946for 1-5 year OS for the UK nomogram.For DFS, the AUC ranged from 0.807-0.948.For those with LG histology, the AUC for OS ranged from 0.610-0.696,and from 0.689-0.831for DFS.For HG histology, the AUC for OS ranged from J o u r n a l P r e -p r o o f 0.730-0.863and from 0.622-0.668.There were no significant differences between the UK and Spanish nomograms for DFS among all patients and among histological subgroups. ConclusionsExisting nomograms for OS and DFS after CRS-HIPEC for PMP are fairly accurate, highlighting their potential utility to predict outcomes in this population.