Lymphovascular invasion in more than one-quarter of small rectal neuroendocrine tumors

Table 1 Demographic and clinical features of patient with rectal neuroendocrine tumors

Characteristic	n = 104
Gender
Male	67
Female	37
Age (yr), median	47 (range, 21-80)
< 60	89
≥ 60	15
Distance from anal verge, mean ± SD (cm)	8.09 ± 3.26 (range, 3-20)
Type of endoscopic resection
EMR	6
ESMR_L	57
ESD	41
Tumor size, mean ± SD (mm)	5.4 ± 2.4 (range, 1.2-10)
≤ 5	62
> 5 and ≤ 10	42
Tumor depth
Mucosa	3
Submucosa	101
Resection margin status
R0	88
R1	16
Lateral (+) and deep (-)	1
Lateral (+) and deep (+)	1
Lateral (-) and deep (+)	14
Complications
Yes	1
No	103
Follow-up
Recurrence	0
Died	2

Table 2 Predictive parameters of lymphovascular invasion between hematoxylin and eosin and D2-40 and Elastica van Gieson in small rectal neuroendocrine tumors n (%)

		LVI (H&E only)			LVI (D2-40 and EVG)
	Total	Present	Absent	P vaule	Present	Absent	P vaule
	n = 104	n = 26 (25.0%)	n = 78 (75.0%)		n = 29 (27.9%)	n = 75 (72.1%)
D2-40 and EVG				0.648			-
LVI (+)	29 (27.9)	18 (69.2)	11 (14.1)		-	-
LVI (-)	75 (72.1)	8 (30.8)	67 (85.9)		-	-
Age (yr)	48.20 ± 10.93	50.27 ± 11.28	47.51 ± 10.80	0.282	47.86 ± 11.16	48.33 ± 10.91	0.847
Sex				1.000			0.650
Male	67 (64.4)	17 (65.4)	50 (64.1)		20 (69.0)	47 (62.7)
Female	37 (35.6)	9 (34.6)	28 (35.9)		9 (31.0)	28 (37.3)
AV distance (cm)1	8.09 ± 3.25	8.35 ± 2.72	8.01 ± 3.41	0.687	7.59 ± 2.87	8.25 ± 3.37	0.412
Tumor size				0.038			0.007
≤ 5 mm	62 (59.6)	11 (42.3)	51 (65.4)		11 (37.9)	51 (68.0)
> 5 mm	42 (40.4)	15 (57.7)	27 (34.6)		18 (62.1)	24 (32.0)
Tumor depth				0.571			0.558
Mucosa	3 (2.9)	0 (0)	3 (3.8)		0 (0)	3 (4.0)
Submucosa	101 (97.1)	26 (100)	75 (96.2)		29 (100)	72 (96.0)
Tumor grade				1.000			0.006
Grade 1	95 (91.3)	24 (92.3)	71 (91.0)		20 (69.0)	68 (90.7)
Grade 2	9 (8.7)	2 (7.7)	7 (9.0)		9 (31.0)	7 (9.3)
Ki 67%		1.46 ± 1.01	1.08 ± 1.05	0.113	1.54 ± 1.13	1.03 ± 0.97	0.023
Ki 67 index				0.627			0.213
< 3%	98 (94.2)	24 (92.3)	74 (94.9)		26 (89.7)	72 (96.0)
≥ 3%	6 (5.8)	2 (7.7)	4 (5.1)		3 (10.3)	3 (4.0)
Mitotic count		0.65 ± 0.84	0.39 ± 0.69	0.125	0.82 ± 0.88	0.32 ± 0.97	0.001
Mitosis/10HPF				0.357			0.005
< 2	93 (89.4)	22 (84.6)	71 (91.0)		22 (75.9)	71 (94.7)
≥ 2	11 (10.6)	4 (15.4)	7 (9.0)		7 (24.1)	4 (5.3)

¹The tumor location is measured from anal verge. Bold values: P value < 0.05. HPF: High power field; LVI: Lymphovascular invasion; H&E: Hematoxylin and eosin stain.

Table 3 Multivariate analyses of clinicopathological factors predictive of lymphovascular invasion in patients with rectal neuroendocrine tumors

	Lymphovascular invasion		P value
	HR	95% CI
Tumor size > 5 mm	1.694	0.639-4.491	0.289
Tumor grade Grade 2	4.095	1.321-12.692	0.015

Bold values: P value < 0.05. HR: Hazard ratio; HPF: High power field.

Table 4 Outcomes of endoscopic resection procedures in relation to tumor size, margin status, and lymphovascular invasion n (%)

	ESMR-L	ESD	P vaule
	n = 57	n = 41
LVI			0.955
Absent	42 (58.3)	30 (41.7)
Present	15 (58.2)	11 (42.3)
Tumor size			0.192
≤ 5 mm	38 (66.7)	22 (53.7)
> 5 mm	19 (33.3)	19 (46.3)
Resection outcome			0.504
Complete (R0)	50 (87.7)	34 (82.9)
Incomplete (R1)	7 (12.3)	7 (17.1)
Safety resection margin (μm)	725 ± 872	322 ± 348	0.002

Bold values: P value < 0.05. LVI: Lymphovascular invasion.