New insights in diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms

Table 1 World Health Organization classification for gastroenteropancreatic neuroendocrine neoplasms¹

	Differentiation	Mitotic rate (%)	Ki-67 proliferation index (%)
G1 NET	Well-differentiated	< 2	< 3
G2 NET	Well-differentiated	2-20	3-20
G3 NET	Well-differentiated	> 20	> 20
SCNEC	Poorly-differentiated	> 20	> 20
LCNEC	Poorly-differentiated	> 20	> 20
MiNEN	Well- or poorly-differentiated	Variable	Variable

NET: Neuroendocrine tumor; SCNEC: Small cell neuroendocrine carcinoma; LCNEC: Large cell neuroendocrine carcinoma; MiNEN: Mixed neuroendocrine-non-neuroendocrine neoplasm.

¹Data derived from Klimstra et al[1].

Table 2 Clinicopathologic characteristics of gastric neuroendocrine tumor

	Type 1	Type 2	Type 3
Relative frequency (%)	70-80	5-6	10-15
Gender	F > M	F = M	M > F
Cell of origin	ECL	ECL	ECL, EC, etc.
Associated disease	AMAG; Pernicious anemia	MEN1; ZES	None (Sporadic)
Site of tumors	Fundus and corpus	Fundus and corpus, occasionally antrum	Anywhere
Size of tumors	< 1 cm	< 2 cm	2-5 cm
Number of tumors	Multiple	Multiple	Single
Plasma gastrin level	High	High	Normal
Gastric acid output	Low or absent	High	Normal
Metastatic rate (%)	2-5	10-30	50-100
Tumor related death (%)	Approximately 0	< 10	25-30

ECL: Enterochromaffin-like cell; EC: Enterochromaffin cell; F: Female; M: Male; AMAG: Autoimmune metaplastic atrophic gastritis; MEN1: Multiple endocrine neoplasm type 1; ZES: Zollinger-Ellison syndrome.