Classification, clinicopathologic features and treatment of gastric neuroendocrine tumors

Table 1 Features of gastric neuroendocrine tumors

	Type I GNET	Type II GNET	Type III GNET	Type IV GNET
Proportion of GNETs	70%-80%	5%-6%	14%-25%	Rare
Tumor features	Usually multiple, small (1-2 cm), polypoid or intramucosal	Usually multiple, small (1-2 cm), polypoid	Single, large (> 2 cm, mean 5.1 cm)	Single, large (largest 16 cm)
Risk of metastases	2%-5%	10%-30%	50%-100%	100%
Tumor-related death	< 0.5%	< 5%	Well-differentiated: 25%-30%,poorly differentiated: 75%-87%	100% (Mean survival of 6.5-14.9 mo)
Proliferation (Ki67)	< 2%	< 2%	> 2%	> 30%
Immunohistochemistry	CgA, NSE, VMAT 2 positive	CgA positive	CgA negative	Synaptophysin, NSE, PGP9.5 positive;
				CgA negative
Histology	Mitoses (absent or occasionally)	mitoses < 1 per 2 HPFs	Mitoses > 1 per HPF	Severe grade 3 histology

GNET: Gastric neuroendocrine tumor; CgA: Chromogranin A; NSE: Neuron specific enolase; VMAT: Vesicular monoamine transporter; HPF: High power field.