Both G3 NET and NEC still share the same grading cutoffs of a Ki-67 proliferation index of > 20% and/or a mitotic count > 20 per 2 mm2, and although G3 NET typically show lower Ki-67 indices and fewer mitoses than NEC, there is no formal upper limit of Ki-67 index or mitotic count for G3 NET. This evidence concerns the gene MKI67 and neuroendocrine carcinoma.