MKI67 and neuroendocrine carcinoma: According to mitotic count or Ki-67 index, NET is divided into three subgroups: well-differentiated G1 NET with indolent nature and favorable prognosis, moderately-differentiated G2 NET with intermediate risk of metastasis, and poorly-differentiated G3 NET (also termed as neuroendocrine carcinoma, NEC) with frequent metastasis and dismal outcome (1, 2).