MKI67 and neuroendocrine carcinoma: Recently, Milione et al. categorized 136 patients with NEC based on the 2010 classification into three groups (type A: well-differentiated and Ki-67 index 20%–55%; type B: poorly differentiated and Ki-67 index 20%–55%; type C: poorly differentiated and Ki-67 index ≥55%), and compared OS between these three groups.