Underwater vs conventional endoscopic mucosal resection for nonpedunculated colorectal neoplasms: A randomized controlled trial

Table 1 Patient characteristics in the study, n (%)

Characteristics	Total (n = 260)	CEMR (n = 130)	UEMR (n = 130)	P value
Age, median (minimum-maximum)	58 (27-85)	60 (27-83)	59 (32-85)	0.9152
Sex				0.699
Male	165 (63.5)	84 (64.6)	81 (62.3)
Female	95 (36.5)	46 (35.4)	49 (37.7)
Indication for colonoscopy
Abdominal pain	73 (28.1)	42 (32.3)	31 (23.8)	0.129
Screening	60 (23.1)	24 (18.5)	36 (27.7)	0.077
Blood in stool	34 (13.1)	15 (11.5)	19 (14.6)	0.462
Diarrhea	33 (12.7)	17 (13.1)	16 (12.3)	0.852
Constipation	33 (12.7)	17 (13.1)	16 (12.3)	0.852
Post-operative CRC	23 (8.8)	14 (10.8)	9 (6.9)	0.275
Stool change	2 (0.8)	0 (0)	2 (1.5)	0.4981
Weight loss	2 (0.8)	1 (0.8)	1 (0.8)	11
Clinical symptoms
No symptom	85 (32.7)	38 (29.3)	47 (36.1)	0.234
Abdominal pain	74 (28.5)	40 (30.8)	34 (26.2)	0.410
Diarrhea	35 (13.5)	19 (14.6)	16 (12.3)	0.586
Blood in stool	33 (12.7)	17 (13.1)	16 (12.3)	0.852
Constipation	31 (11.9)	15 (11.5)	16 (12.3)	0.848
Weight loss	2 (0.8)	1 (0.8)	1 (0.8)	11
Hypertension	127 (48.8)	62 (47.7)	65 (50)	0.710
Diabetes	20 (7.7)	8 (6.2)	12 (9.2)	0.352
Kidney failure	3 (1.2)	0 (0)	3 (2.3)	0.2471
Personal history of CRC	11 (4.2)	5 (3.8)	6 (4.6)	0.758
Family history of CRC	4 (1.5)	2 (1.5)	2 (1.5)	11

¹P values were computed with Fisher’s exact test.

²P values were computed with the Mann-Whitney U test.

CEMR: Conventional endoscopic mucosal resection; CRC: Colorectal cancer; UEMR: Underwater endoscopic mucosal resection.

Table 2 Endoscopic and pathological characteristics of the colorectal lesions, n (%)

Characteristics	Total (n = 260)	CEMR (n = 130)	UEMR (n = 130)	P value
Location of lesion
Rectum	67 (25.8)	28 (21.5)	39 (30.0)	0.119
Sigmoid colon	98 (37.7)	52 (40.0)	46 (35.4)	0.443
Descending colon	16 (6.2)	10 (7.7)	6 (4.6)	0.302
Transverse colon	34 (12.3)	17 (13.1)	17 (13.1)	1
Ascending colon	36 (13.8)	18 (13.8)	18 (13.8)	1
Cecum	9 (3.5)	5 (3.8)	4 (3.1)	11
Size, median (minimum-maximum) (mm)	20 (10-30)	12 (10-30)	12 (10-25)	0.7582
10-19	233 (89.6)	117 (90.0)	116 (89.2)	0.839
20-30	27 (10.4)	13 (10.0)	14 (10.8)
Paris classification				0.600
0-Is	172 (66.1)	88 (67.7)	84 (64.6)
0-IIa/0-IIb	88 (33.9)	42 (32.3)	46 (35.4)
NICE classification				0.656
Type 1	22 (8.5)	10 (7.7)	12 (9.2)
Type 2	238 (91.5)	120 (92.3)	118 (90.8)
WHO classification
Nonneoplastic polyp	14 (5.4)	6 (4.6)	8 (6.2)	0.583
Tubular adenoma	161 (61.9)	76 (58.5)	85 (65.4)	0.250
Tubulo-villous adenoma	36 (13.8)	21 (16.2)	15 (11.5)	0.281
Serrated lesion	49 (18.8)	27 (20.8)	22 (16.9)	0.428
Vienna classification
No dysplasia	21 (8.1)	9 (6.9)	12 (9.2)	0.495
Low-grade dysplasia	209 (80.4)	108 (83.1)	101 (77.7)	0.274
High-grade dysplasia	26 (10.0)	10 (7.7)	16 (12.3)	0.215
Superficial cancer	4 (1.5)	3 (2.3)	1 (0.8)	0.6221

¹P values were computed with Fisher’s exact test.

²P values were computed with the Mann-Whitney U test.

CEMR: Conventional endoscopic mucosal resection; NICE: Narrow band imaging international colorectal endoscopic classification; UEMR: Underwater endoscopic mucosal resection; WHO: World Health Organization.

Table 3 Study outcomes (intention-to-treat analysis), n (%)

Outcomes	CEMR (n = 130)	UEMR (n = 130)	P value
En bloc resection			0.0141
Yes	123 (94.6)	130 (100)
No	7 (5.4)	0 (0)
R0			0.007
Yes	112 (90.3)	120 (98.4)
No	12 (9.7)	2 (1.6)
Procedure time (IQR), second	185 (35-900)	65 (15-610)	< 0.0012
Bleeding			0.003
Yes	13 (10.0)	2 (1.5)
No	117 (90.0)	128 (98.5)
Hemoclip (IQR)	3 (1-9)	2 (1-9)	< 0.0012

¹P values were computed with Fisher’s exact test.

²P values were computed with the Mann-Whitney U test.

CEMR: Conventional endoscopic mucosal resection; IQR: Interquartile range; UEMR: Underwater endoscopic mucosal resection.

Table 4 Study outcomes (per-protocol analysis), n (%)

Outcomes	CEMR (n = 124)	UEMR (n = 122)	P value
En bloc resection			0.0141
Yes	117 (94.4)	122 (100)
No	7 (5.6)	0 (0)
R0			0.007
Yes	112 (90.3)	120 (98.4)
No	12 (9.7)	2 (1.6)
Procedure time (IQR), second	185 (35-900)	65 (15-610)	< 0.0012
Bleeding			0.004
Yes	13 (10.5)	2 (1.6)
No	111 (89.5)	120 (98.4)
Hemoclip (IQR)	3 (1-9)	2 (1-9)	< 0.0012

¹P values were computed with Fisher’s exact test.

²P values were computed with the Mann-Whitney U test.

CEMR: Conventional endoscopic mucosal resection; IQR: Interquartile range; UEMR: Underwater endoscopic mucosal resection.