Supplementary Material for: High-Grade Progression Confers Poor Survival in Pancreatic Neuroendocrine Tumors

<b><i>Introduction:</i></b> Little is known about how pancreatic neuroendocrine tumors (PanNETs) evolve over time and if changes toward a more aggressive biology correlate with prognosis. The purpose of this study was to characterize changes in PanNET differentiation and proliferation over time and to correlate findings to overall survival (OS). <b><i>Patients and Methods:</i></b> In this retrospective cohort study, we screened 475 PanNET patients treated at Uppsala University Hospital, Sweden. Sporadic patients with baseline and follow-up tumor samples were included. Pathology reports and available tissue sections were reevaluated with regard to tumor histopathology and Ki-67 index. <b><i>Results:</i></b> Forty-six patients with 106 tumor samples (56 available for pathology reevaluation) were included. Median Ki-67 index at diagnosis was 7% (range 1–38%), grade 1 <i>n</i> = 8, grade 2 <i>n</i> = 36, and grade 3 <i>n</i> = 2. The median change in Ki-67 index (absolute value; follow-up – baseline) was +14% (range –11 to +80%). Increase in tumor grade occurred in 28 patients (63.6%), the majority from grade 1/2 to grade 3 (<i>n</i> = 24, 54.5%). The patients with a high-grade progression had a median OS of 50.2 months compared to 115.1 months in patients without such progression (hazard ratio 3.89, 95% CI 1.91–7.94, <i>p</i> &lt; 0.001). <b><i>Conclusions:</i></b> A longitudinal increase in Ki-67 index and increase in tumor grade were observed in a majority of PanNETs included in this study. We propose that increase in Ki-67 index and high-grade progression should be investigated further as important biomarkers in PanNET.