International Validation of a Nomogram to Predict Recurrence after Resection of Grade 1 and 2 Nonfunctioning Pancreatic Neuroendocrine Tumors

Charlotte M. Heidsma, Stijn van Roessel, Susan van Dieren, Anton F. Engelsman, Oliver Strobel, Markus W. Buechler, Simon Schimmack, Julie Perinel, Mustapha Adham, Vikram Deshpande, Josefine Kjaer, Olov Norlen, Anthony J. Gill, Jaswinder S. Samra, Anubhav Mittal, Frederik J. H. Hoogwater, Florian Primavesi, Stefan Stattner, Marc G. Besselink, Casper H. J. van EijckE. J. M. Nieveen van Dijkum

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    Background: Despite the low recurrence rate of resected nonfunctional pancreatic neuroendocrine tumors (NF-pNETs), nearly all patients undergo long-term surveillance. A prediction model for recurrence may help select patients for less intensive surveillance or identify patients for adjuvant therapy. The objective of this study was to assess the external validity of a recently published model predicting recurrence within 5 years after surgery for NF-pNET in an international cohort. This prediction model includes tumor grade, lymph node status and perineural invasion as predictors. Methods: Retrospectively, data were collected from 7 international referral centers on patients who underwent resection for a grade 1-2 NF-pNET between 1992 and 2018. Model performance was evaluated by calibration statistics, Harrel's C-statistic, and area under the curve (AUC) of the receiver operating characteristic curve for 5-year recurrence-free survival (RFS). A sub-analysis was performed in pNETs >2 cm. The model was improved to stratify patients into 3 risk groups (low, medium, high) for recurrence. Results: Overall, 342 patients were included in the validation cohort with a 5-year RFS of 83% (95% confidence interval [CI]: 78-88%). Fifty-eight patients (17%) developed a recurrence. Calibration showed an intercept of 0 and a slope of 0.74. The C-statistic was 0.77 (95% CI: 0.70-0.83), and the AUC for the prediction of 5-year RFS was 0.74. The prediction model had a better performance in tumors >2 cm (C-statistic 0.80). Conclusions: External validity of this prediction model for recurrence after curative surgery for grade 1-2 NF-pNET showed accurate overall performance using 3 easily accessible parameters. This model is available via

    Original languageEnglish
    Pages (from-to)571–579
    Number of pages9
    Early online date29-Jul-2021
    Publication statusPublished - May-2022


    • Prediction model
    • Risk factors
    • Recurrence
    • Nonfunctional pancreatic neuroendocrine tumors

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