Endoscopic diagnosis and management of type I neuroendocrine tumors

Table 1 Characteristics of gastric neuroendocrine tumors

Characteristic	Type I GNETs	Type II GNETs	Type III GNETs
Proportion of all GNETs	70%-80%	5%-10%	10%-15%
Associated disease	Chronic atrophic gastritis	MEN type 1/ZES	None
Gender	Women > men	Women = men	Women < men
Tumor number	≥ 1	≥ 1	1
Tumor size	< 10 mm	< 10 mm	Often > 20 mm
Tumor location	Fundus or corpus	Fundus or corpus	Any region
Histology	Well differentiated	Well differentiated	From well to poorly differentiated
Invasion depth	Mucosa or submucosa	Mucosa or submucosa	Any depth
Serum gastrin level	High	High	Normal
Gastric pH	Low	High	Normal
Metastasis risk	2%-5%	10%-20%	> 50%
Tumor-related death	0	< 10%	25%-30%
Prognosis	Excellent	Good	Poor

GNET: Gastric neuroendocrine tumor; MEN: Multiple endocrine neoplasia; ZES: Zollinger-Ellison syndrome.

Table 2 Histological grading of gastrointestinal neuroendocrine neoplasms

ENETSgrading	Mitotic index(× 10 HPF)	Ki-67 proliferationindex (%)	WHO classification 2010
G1	< 2	≤ 2	NET G1 (carcinoid)
G2	2-20	3-20	NET G2
G3	> 20	> 20	NEC G3; large-cell or small-cell type

ENETS: European neuroendocrine tumor society; HPF: High power field; NET: Neuroendocrine tumor; NEC: Neuroendocrine carcinoma.