Long-term outcomes of endoscopic resection of 1-1.5 cm sized grade 1 rectal neuroendocrine tumor: A retrospective study

Table 1 Baseline characteristics, medians (Q1, Q3)/n (%)

	Study population (n = 1056)	≥ 0 cm and < 0.5 cm (n = 659)	≥ 0.5 cm and < 1 cm (n = 354)	≥ 1 cm and < 1.5 cm (n = 43)	P value
Age (years)	46 (38-54)	46 (38-54)	45 (37-55)	48 (38-61.5)	0.44
Sex					0.87
Male	636 (60.2)	401 (71)	209 (59)	26 (60.5)
Female	421 (39.8)	259 (29)	145 (41)	17 (39.5)
Rectal NET size (cm)	0.4 (0.3-0.6)	0.3 (0.2-0.4)	0.6 (0.5-0.7)	1.0 (1.0-1.1)	< 0.01
Distance from anal verge (cm)	7 (5-10)	7 (5-10)	8 (5-10)	6.5 (5-8)	0.13
Therapy methods					< 0.01
Endoscopic resection	932 (88.2)	621 (94.1)	284 (80.2)	27 (62.8)
Surgical resection	125 (11.8)	39 (5.9)	70 (19.8)	16 (37.2)
Endoscopic methods					< 0.01
ESD	180 (19.3)	67 (10.8)	100 (35.2)	13 (48.1)
EMR	752 (80.7)	554 (89.2)	184 (64.8)	14 (51.9)
Surgical methods					0.69
TEM	99 (79.2)	32 (82.1)	54 (77.1)	13 (81.3)
Transanalrectal resection	18 (14.4)	5 (12.8)	12 (17.1)	1 (6.3)
Lower anterior resection	8 (6.4)	2 (5.1)	4 (5.7)	2 (12.4)
WHO grade					0.02
Grade 1	627 (59.3)	401 (60.8)	194 (54.8)	32 (74.4)
Grade 2	19 (1.8)	7 (1.1)	12 (3.4)	0
Grade 3	0	0	0	0
Missing	411 (38.9)	252 (38.2)	148 (41.8)	11 (25.6)
Resection margin					0.57
Negative	1025 (97.0)	641 (97.1)	343 (96.9)	41 (95.4)
Positive	26 (2.5)	14 (2.1)	10 (2.8)	2 (4.6)
Uncheckable	6 (0.5)	5 (0.8)	1 (0.3)	0 (0)
Depth					< 0.01
1a	1014 (95.9)	660 (100.0)	353 (99.7)	1 (2.3)
1b	41 (3.9)	0 (0)	0 (0)	41 (95.4)
2	2 (0.2%)	0 (0)	1 (0.3)	1 (2.3)
Lymphovascular invasion					0.47
Absent/not identified	1040 (98.4)	648 (98.2)	350 (98.9)	42 (97.7)
Present	5 (0.5)	2 (0.3)	3 (0.9)	0 (0.0)
Missing	12 (1.1)	10 (1.5)	1 (0.2)	1 (2.3)

NET: Neuroendocrine tumor; ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; TEM: Transanal endoscopic microsurgery; WHO: World Health Organization.

Table 2 Baseline characteristics with propensity score matching between groups, n (%)

Group	Before PS matching				After PS matching
	Total (n = 932)	≥ 0 cm and < 1 cm (n = 905)	≥ 1 cm and < 1.5 cm (n = 27)	P value	Total (n = 252)	≥ 0 cm and < 1 cm (n = 225)	≥ 1 cm and < 1.5 cm (n = 27)	SMD
Age, median (IQR)	46.0 (38.0, 54.0)	46.0 (38.0, 54.0)	49.0 (38.0, 61.5)	0.07	46.0 (38.0, 58.0)	46.0 (38.0, 58.0)	49.0 (38.0, 61.5)	0.17
Sex				0.27				0.02
Male	560 (60.0)	541 (59.7)	19 (70.4)		174 (69.1)	155 (68.9)	19 (70.4)
Female	373 (40.0)	365 (40.3)	8 (29.6)		78 (31.0)	70 (31.1)	8 (29.6)
Endoscopic resection				< 0.01				0.12
ESD	180 (19.3)	167 (18.43)	13 (48.15)		114 (45.2)	101 (44.9)	13 (48.2)
EMR	753 (80.7)	739 (81.57)	14 (51.85)		138 (54.8)	124 (55.1)	14 (51.8)

PS: Propensity score; IQR: Interquartile range; ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; SMD: Standardized mean difference.

Table 3 Comparison of resection margins and recurrence between groups, n (%)

	Total (n = 252)	0-1 cm (n = 225)	1-1.5 cm (n = 27)	P value
Resection margin (R0)				0.2210
Negative RM	245 (97.2)	220 (97.8)	25 (92.6)
Positive RM	6 (2.4)	4 (1.8)	2 (7.4)
Uncheckable	1 (0.4)	1 (0.4)	0 (0)
Recurrence				1.0000
No recur	251 (99.6)	224 (99.6)	27 (100)
Intramural recurrence	0 (0)	0 (0)	0 (0)
Extracolonic recurrence	1 (0.4)	1 (0.4)	0 (0)
Synchronous recurrence	0 (0)	0 (0)	0 (0)
Lymphovascular invasion
No	248 (48.4)	221 (98.2)	27 (100)
Missing	4 (1.6)	4 (1.8)	0 (0)

RM: Resection margin.