Angiogenic markers endoglin and vascular endothelial growth factor in gastroenteropancreatic neuroendocrine tumors

Table 1 Patient and tumor characteristics n (%)

Patients (n = 41)
Age (yr)
mean ± SD	47 ± 14
Range	20-77
Sex
Male	17 (41.5)
Female	24 (58.5)
Tumor type
Carcinoid	12 (29.3)
Functional PNET	19 (46.3)
Non-functional PNET	10 (24.4)
Tumor grade
Well-differentiated NET	13 (31.7)
Well-differentiated NEC	26 (63.4)
Poorly differentiated NEC	1 (2.4)
Unknown	1 (2.4)
Metastases
Present	26 (63.4)
Lymph node only	9 (34.6)
Liver only	7 (26.9)
Both	10 (38.5)
Absent	15 (36.6)
Tumors (n = 60)
Primary or metastatic tissues
Primary	45 (75.0)
Metastasis	15 (25.0)
Angio-invasion
Present	11 (18.3)
Absent	49 (81.7)
Tumor size (mean ± SD, cm)
Carcinoids	3.4 ± 2.7
Functional PNETs	1.9 ± 1.7
Non-functional PNETs	3.6 ± 2.4

PNETs: Pancreatic neuroendocrine tumors; NET: Neuroendocrine tumor; NEC: Neuroendocrine carcinoma.

Table 2 Mean endoglin and vascular endothelial growth factor levels in gastroenteropancreatic neuroendocrine tumors in relation to clinicopathological parameters

	Endoglin (ng/mg)				VEGF (pg/mg)
	n	mean	SE	P	n	mean	SE	P
Tissues
Normal	38	12.1	2.0	< 0.012	38	75.0	9.5	< 0.012
Tumor	27	26.8	4.5		26	316.8	46.0
Tumor type
Carcinoid	8	35.3	11.4	0.37	8	354.9	72.0	0.67
Functional PNET	14	25.4	4.7		13	274.4	46.7
Non-functional PNET	5	16.8	8.7		5	366.2	186.8
Origin
Primary tumors	19	18.8	3.9	< 0.012	18	293.2	52.0	0.45
Metastatic tumors	8	45.7	9.0		8	369.9	95.8
WHO classification
Well-differentiated NETs	6	7.6	5.2	0.0212	6	200.2	52.8	0.211
Well-differentiated NECs	20	32.9	4.0		19	328.5	60.2
Poorly-differentiated NECs	1	19.0	ND		1	795.0	ND
Primary tumors: metastases
Present	12	24.8	5.2	0.042	11	339.5	76.4	0.28
Absent	7	8.5	3.5		7	220.6	54.8

¹Result of unpaired t test to compare well-differentiated neuroendocrine tumors (NETs) with well-differentiated neuroendocrine carcinomas (NECs);

²P values are considered statistically significant. VEGF: Vascular endothelial growth factor; PNET: Pancreatic neuroendocrine tumor; ND: Not described.

Table 3 Microvessel density scores in gastroenteropancreatic neuroendocrine tumors in relation to clinicopathological parameters

	MVD-endoglin				MVD-CD31
	n	mean1	SE1	P	n	mean1	SE1	P
Tumor type
Carcinoid	11	55	107	0.30	13	123	23	0.75
Functional PNET	24	65	8		23	106	18
Non-functional PNET	14	85	18		14	100	17
Origin
Primary tumors	36	66	8	0.58	37	111	13	0.69
Metastatic tumors	13	75	15		13	101	24
WHO classification
Well-differentiated NETs	13	69	18	0.932	13	76	12	0.082
Well-differentiated NECs	33	67	7		34	121	15
Poorly-differentiated NECs	1	212			1	82
Primary tumors: metastases
Present	19	66	9	0.96	20	138	18	0.053
Absent	17	67	14		17	88	15

¹Values × 1000 pixels per area;

²Result of unpaired t test to compare well-differentiated neuroendocrine tumors (NETs) with well-differentiated neuroendocrine carcinomas (NECs);

³P values are considered statistically significant. MVD: Microvessel density; PNET: Pancreatic neuroendocrine tumor.