Clinical impact of atypical endoscopic features in rectal neuroendocrine tumors

Table 1 Characteristics of the 247 patients with rectal neuroendocrine tumor n (%)

	Value
Age, mean ± SD (range), yr	51.56 ± 10.69 (27-76)
Sex
Male	91 (36.8)
Female	156 (63.2)
Tumor size, mean ± SD (mm)	5.76 ± 2.76
Resection type
Endoscopic resection	208 (84.2)
TEM or TAE	22 (8.9)
Radical resection	16 (6.5)
None	1 (0.4)
Distant organ metastasis at diagnosis
Negative	245 (99.2)
Positive	2 (0.8)
LN metastasis
Negative	232 (93.9)
Positive	15 (6.1)

TEM: Transanal endoscopic microsurgery; TAE: Transanal excision; LN: Lymph node.

Table 2 Univariate and multivariate analyses of clinical factors associated with lymph node metastasis in patients with rectal neuroendocrine tumors n (%)

	Univariate analysis			Multivariate analysis
	Metastasis (-)	Metastasis (+)	P value	OR (95%CI)	P value
Gender			0.183	-	-
Male	144 (92.3)	12 (7.7)
Female	88 (96.7)	3 (3.3)
Age (yr)			1.000	-	-
≤ 50	113 (94.2)	7 (5.8)
> 50	119 (93.7)	8 (6.3)
Size (mm)			< 0.001	11.53 (2.51-52.93)	0.002
< 10	219 (98.6)	3 (1.4)
≥ 10, < 20	13 (59.1)	9 (40.9)
≥ 20	0 (0)	3 (100)
Tumor shape			< 0.001	-	-
Sessile	205 (97.6)	5 (2.4)
Semipedunculated	27 (77.1)	8 (22.9)
Ulcerofungating	0 (0)	2 (100)
Surface change			< 0.001	27.44 (5.96-126.34)	< 0.001
Smooth	222 (97.8)	5 (2.2)
Depressed/eroded	10 (55.6)	8 (44.4)
Ulcerated	0 (0)	2 (100)
Color			< 0.001	-	-
Normal or yellow	210 (96.8)	7 (3.2)
Hyperemia	22 (73.3)	8 (26.7)
Atypical features, any			< 0.001	4.38 (0.92-20.80)	0.064
Typical features	189 (98.4)	3 (1.6)
Atypical features	43 (78.2)	12 (21.8)

Table 3 Atypical features of rectal neuroendocrine tumors according to tumor size n (%)

	Typical (n = 192)	Atypical (n = 55)	P value
Tumor size (mm)			< 0.001
< 10	186 (83.8)	36 (16.2)
≥ 10, < 20	6 (27.3)	16 (72.7)
≥ 20	0 (0)	3 (100)

Table 4 Association between endoscopic features and metastasis in rectal neuroendocrine tumors < 10 mm and 10-19 mm in diameter n (%)

	Metastasis (-)	Metastasis (+)	P value
< 10 mm in diameter
Shape			0.155
Sessile	199 (99.0)	2 (1.0)
Semipedunculated	20 (95.2)	1 (4.8)
Surface change			0.005
Smooth	212 (99.1)	2 (0.9)
Depression/erosion	7 (87.5)	1 (12.5)
Color			0.627
Yellow	203 (98.5)	3 (1.5)
Hyperemia	16 (100)	0 (0)
10-19 mm in diameter
Shape			0.548
Sessile	6 (66.7)	3 (33.3)
Semipedunculated	7 (53.8)	6 (46.2)
Surface change
Smooth	10 (76.9)	3 (23.1)	0.041
Depression/erosion	3 (33.3)	6 (66.7)
Color			0.665
Yellow	7 (63.6)	4 (36.4)
Hyperemia	6 (54.5)	5 (45.5)

Table 5 Association between atypical endoscopic features of rectal neuroendocrine tumors and immunohistochemical staining results n (%)

	Typical feature	Atypical feature	P value
L-cell			0.008
(-)	27 (62.8)	16 (37.2)
(+)	142 (81.6)	32 (18.4)
EC-cell			0.464
(-)	162 (78.3)	45 (21.7)
(+)	7 (70.0)	3 (30.0)
Serotonin			0.306
(-)	161 (78.5)	44 (21.5)
(+)	8 (66.7)	4 (33.3)
Somatostatin			1.000
(-)	161 (77.8)	46 (22.2)
(+)	8 (80.0)	2 (20.0)
GLP1			0.021
(-)	57 (69.5)	25 (30.5)
(+)	112 (83.0)	23 (17.0)
PYY1			0.513
(-)	72 (75.8)	23 (24.2)
(+)	97 (79.5)	25 (20.5)
PPY1			0.443
(-)	88 (75.9)	28 (24.1)
(+)	81 (80.2)	20 (19.8)

Table 6 Association between atypical features and L-cell type in rectal neuroendocrine tumors n (%)

	L-cell (-)	L-cell (+)	P value
Tumor shape			0.107
Sessile	34 (18.4)	151 (81.6)
Semipedunculated	8 (25.8)	23 (74.2)
Ulcerofungating	1 (100)	0 (0)
Surface change			0.022
Smooth	36 (18.0)	164 (82.0)
Depression/erosion	6 (37.5)	10 (62.5)
Ulceration	1 (100)	0 (0)
Color			< 0.001
Normal or yellow	31 (16.1)	162 (83.9)
Hyperemia	12 (50.0)	12 (50.0)