Role of surgical treatments in high-grade or advanced gastroenteropancreatic neuroendocrine neoplasms

Table 1 Classification for gastroenteropancreatic neuroendocrine neoplasms by World Health Organization

Terminology	Differentiation	Grade	Ki67 index, %	Mitotic count, 2 mm2
NET, G1	Well differentiated	Low	< 3	< 2
NET, G2	Well differentiated	Intermediate	3–20	2–20
NET, G3	Well differentiated	High	> 20	> 20
NEC, G3	Poorly differentiated	High	> 20	> 20

NET: Neuroendocrine tumor; NEC: Neuroendocrine carcinoma.

Table 2 Milan neuroendocrine neoplasms criteria

	Milan selection criteria of GEP-NEN LM
1	Low grade NEN
2	Portal drainage of the primary tumor with complete resection of extrahepatic disease
3	Liver involvement < 50%
4	Duration of stable disease over 6 mo
5	Age < 60 yr (relative criteria)

GEP-NEN: Gastroenteropancreatic neuroendocrine neoplasms; LM: Liver metastasis.