Usefulness of a novel slim type FlushKnife-BT over conventional FlushKnife-BT in esophageal endoscopic submucosal dissection

Table 1 Patient and lesion characteristics

	FlushKnife-BT (n = 6)	FlushKnife-BTS (n = 7)	P vaule1
Male/Female	32/12	42/1	0.559
Age, median (range), years	73.5 (68-78)	57 (57-74)	0.0235
Lesion site Ut/Mt/Lt	0/4/2	0/6/1	0.559
Circumference of the resected area, median (range)	68% (25-100)	75% (50-92)	0.599
Major axis diameter of the resected specimen, median (range), mm	39.5 (30-55)	40 (31-60)	0.277
Resected area, median (range), mm²	1117 (636-2547)	1193 (511-2418)	0.943
Major axis diameter of the tumor3, median (range), mm	33 (19-42)	32 (25-50)	0.616
Histology of the tumor HGIN/SCC	0/6	0/7	0.000
Depth of the tumor EP/LPM/MM	0/5/1	1/5/1	0.629

¹The Mann-Whitney U test was used to compare continuous variables, and the chi-squared test or Fisher's exact probability test was used to compare categorical variables;

²One patient had multiple esophageal lesions treated by endoscopic submucosal dissection;

³In the case of multiple lesions resected simultaneously, the maximum distance between the edges of each tumor was defined as the major axis diameter of the tumor. FlushKnife-BT: Ball-tipped FlushKnife; FlushKnife-BTS: A novel slim type FlushKnife-BT.

Table 2 Outcomes of endoscopic submucosal dissection by novel slim type ball-tipped FlushKnife and ball-tipped FlushKnife

	FlushKnife-BT (n = 6)	FlushKnife-BTS (n = 7)	P vaule1
Use of the thread-traction method, yes/no	3/3	2/5	0.592
Procedure time, median (range), min	48 (24-106)	33 (27-51)	0.389
Treatment speed, median (range), mm2/min	25.5 (19.6-30.3)	44.2 (15.5-55.4)	0.0633
Number of times the knife was replaced, median (range), times	5.5 (4-10)	1 (0-3)	0.0025
Frequency of knife replacement, median (range), times/hour	7.02 (4.23-15)	1.76 (0-5.45)	0.0065
En bloc resection rate	6/6 (100%)	7/7 (100%)	0.000
Adverse events, Perforation/muscle injury/postoperative bleeding	0/1/0	0/0/0	0.462

¹The Mann-Whitney U test was used to compare continuous variables, and the χ² test or Fisher's exact probability test was used to compare categorical variables. FlushKnife-BT: Ball-tipped FlushKnife; FlushKnife-BTS: A novel slim type FlushKnife-BT.

Table 3 Treatment speed of endoscopic submucosal dissection for a resected size more than 1000 mm²

	FlushKnife-BT (n = 4)	FlushKnife-BTS (n = 4)	P vaule
Treatment speed, median (range), mm2/min	24.4 (19.6-27.7)	47.4 (44.2-55.4)	0.0209

FlushKnife-BT: Ball-tipped FlushKnife; FlushKnife-BTS: A novel slim type FlushKnife-BT.