Reappraisal of Malignant Risk Assessment for Small (≤20 mm) Non-functioning Pancreatic Neuroendocrine Tumors

BackgroundOptimal management of non-functioning pancreatic neuroendocrine tumors (PanNETs) <= 20 mm is controversial. The biological heterogeneity of these tumors poses challenges when deciding between resection and observation.MethodsIn this multicenter, retrospective cohort study, we analyzed all patients (n = 78) who underwent resection of non-functioning PanNETs <= 20 mm at three tertiary medical centers from 2004 to 2020 to assess the utility of preoperatively available radiological features and serological biomarkers of non-functioning PanNETs in choosing an optimal surgical indication. The radiological features included non-hyper-attenuation pattern on enhancement computed tomography (CT; hetero/hypo-attenuation) and main pancreatic duct (MPD) involvement, and serological biomarkers included elevation of serum elastase 1 and plasma chromogranin A (CgA) levels.ResultsOf all small non-functioning PanNETs, 5/78 (6%) had lymph node metastasis, 11/76 (14%) were WHO grade II, and 9/66 (14%) had microvascular invasion; 20/78 (26%) had at least one of these high-risk pathological factors. In the preoperative assessment, hetero/hypo-attenuation and MPD involvement were observed in 25/69 (36%) and 8/76 (11%), respectively. Elevated serum elastase 1 and plasma CgA levels were observed in 1/33 (3%) and 0/11 (0%) patients, respectively. On multivariate logistic regression analysis, hetero/hypo-attenuation (odds ratio [OR] 6.1, 95% confidence interval [CI] 1.7-22.2) and MPD involvement (OR 16.8, 95% CI 1.6-174.3) were significantly associated with the high-risk pathological factors. The combination of the two radiological worrisome features correctly predicted non-functioning PanNETs with high-risk pathological factors, with about 75% sensitivity, 79% specificity, and 78% accuracy.ConclusionsThis combination of radiological worrisome features can accurately predict non-functioning PanNETs that may require resection.

Automated summary

This study aimed to assess the utility of preoperatively available radiological features and serological biomarkers in choosing an optimal surgical indication for non-functioning pancreatic neuroendocrine tumors (PanNETs). The combination of hetero/hypo-attenuation and main pancreatic duct involvement accurately predicted high-risk pathological factors. These findings suggest the potential for guiding surgical decisions for non-functioning PanNETs.