External validation of a nomogram to predict malignancy risk in patients with intraductal papillary mucinous neoplasms, using Eastern and Western cohorts

Abstract

Introduction: Intraductal papillary mucinous neoplasm (IPMN) is premalignant pancreatic lesion. International guidelines suggest several treatments and malignancy predictors but offer limited predictors of individual risk. A nomogram to predict individual IPMN malignancy risk was released with good diagnostic performance, based on a cohort of 2258 Korean or Japanese patients with IPMN. This study validated a nomogram to predict malignancy risk and invasiveness of IPMN, using Eastern and Western cohorts. Method: We collected clinicopathological and radiological data of patients who underwent pancreas resection for IPMN at 4 centers each in Eastern and Western countries. After excluding patients with ≥1 missing malignancy predictor in the nomogram (main pancreatic duct diameter, cyst size, presence of mural nodule, serum CEA and CA19-9 levels, and age), we analyzed data of the remaining 393 patients (Eastern: n=265; Western: n=128). Result: Although mean age, sex, log value of serum CA19-9, tumor location, main duct diameter, cyst size and presence of mural nodule differed between the Korea/Japan, Eastern and Western cohorts, rates of malignancy and invasive cancer did not significantly differ. Areas under the receiver operating characteristics curve (AUC) values using the nomogram to predict malignancy were Eastern: 0.745, Western: 0.856, and combined cohorts: 0.776; and to predict invasiveness were Eastern: 0.736, Western: 0.891, and combined cohorts: 0.788. Conclusion: External validation of the nomogram showed good performance in predicting malignancy and invasive cancer in both Eastern and Western IPMN patients. The nomogram could be globally applicable to decide customized treatment options for patients with IPMN.