MKI67 and neuroendocrine carcinoma: According to World Health Organization (WHO) 2010 classification, GEP-NETs are grouped into 3 as follows: well differentiated tumors separated into low-grade (G1) (mitotic count <2/10 high-power field (HPF) and/or Ki-67 index <3%) and intermediate-grade (G2) (mitotic count 2-20/10 HPF and/or Ki-67 index 3-20%), and poorly differentiated tumors as high-grade (G3) neuroendocrine carcinomas (mitotic count >20/10 HPF and/or Ki-67 index >20%) (7,8).