The World Health Organization (WHO) adopted and modified the European Neuroendocrine Tumor Society (ENETS) grading system in 2010 and 2017, respectively, in which PanNETs were defined as G1, G2, and G3 based on the cut-off point of the Ki67 proliferative index and mitotic rate [16,17,18]. This evidence concerns the gene MKI67 and neoplasm.