What types of early gastric cancer are indicated for endoscopic ultrasonography staging of invasion depth?

Table 1 Patient characteristics

Total no. of lesions (patients)	153 (140)
Mean (± SD) age, years	68.7 ± 10.4
Sex, male/female	102/38
Macroscopic type
0-I /0-IIa/0-IIb /0-IIc	9/51/1/92
Location
Upper/middle/lower	45/69/39
Mean (± SD) tumor size, mm	20.5 ± 14.4
Depth of invasion
M/SM1/SM2	93/17/43
Histology
Differentiated/undifferentiated	118/35
Ulcer scar
Positive/negative	29/124
Criteria for endoscopic resection
Absolute/expanded/non-indication	51/38/64

M: Mucosal cancer; SM1: Submucosal invasive cancer invaded into the submucosal layer < 500 μm from the muscularis mucosa; SM2: Submucosal invasive cancer with invasion of ≥ 500 μm into the submucosal layer.

Table 2 Clinical characteristics of the 21 inconclusive cases

Tumor-related factors		No. of inconclusive cases (%)	P value
Macroscopic type			< 0.0001
I	(n = 9)	9 (100)
IIa	(n = 51)	7 (13.7)
IIc	(n = 92)	5 (5.4)
Location			0.03
Upper	(n = 45)	3 (6.7)
Middle	(n = 69)	8 (11.6)
Lower	(n = 39)	10 (25.6)
Histology			0.16
Differentiated	(n = 118)	19 (16.1)
Undifferentiated	(n = 35)	2 (5.7)
Ulcer scar			0.37
Positive	(n = 29)	2 (6.9)
Negative	(n = 124)	19 (15.3)
Criteria for ER			0.58
Absolute	(n = 51)	9 (17.6)
Expanded	(n = 38)	5 (13.2)
Non-indication	(n = 64)	7 (10.3)

ER: Endoscopic resection.

Table 3 Comparison of the invasion depth diagnosis between endoscopic ultrasonography and conventional endoscopy

	Clinical diagnosis	Histologic diagnosis		EUSdiagnosis		P2	Histologicdiagnosis		Accuracy	P (vs EUS)
		M/SM1	SM2	Overall accuracy	Accuracy1		M/SM1	SM2
Diagnosis	M/SM1	81	9	71.2	82.6		97	18	79.7	0.54
	SM2	14	28				13	25
Macroscopic type						0.30
I	M/SM1	-	-	-	-		5	1	88.9	-
	SM2	-	-				0	3
IIa/IIb	M/SM1	26	4	67.3	77.8		32	5	78.8	0.90
	SM2	6	9				6	9
IIc	M/SM1	55	5	80.4	85.1		60	12	79.3	0.32
	SM2	8	19				7	13
Location						0.55
Upper	M/SM1	21	2	74.4	80		24	4	80.0	> 0.99
	SM2	6	11				5	12
Middle	M/SM1	40	7	69.9	78.5		44	11	78.3	0.98
	SM2	7	11				4	10
Lower	M/SM1	19	2	62.2	85.2		29	3	82.1	> 0.99
	SM2	2	4				4	3
Histology						0.79
Diff.	M/SM1	71	10	70.4	83		77	12	80.5	0.63
	SM2	8	17				11	18
Undiff.	M/SM1	9	1	75.0	84		20	6	77.1	> 0.99
	SM2	4	12				2	7
Ulcer scar						< 0.0001
Positive	M/SM1	3	2	46.7	50		7	4	58.6	0.51
	SM2	12	11				8	10
Negative	M/SM1	77	7	75.6	89.4		90	14	84.7	0.29
	SM2	4	16				5	15
Indication for ER						< 0.0001
Absolute	M/SM1	37	-	80.4	97.4b		43	-	84.3f	0.07
	SM2	1	-				8	-
Expanded	M/SM1	28	-	75.7	87.5d		33	-	86.8h	> 0.99
	SM2	4	-				5	-
Non-indication	M/SM1	12	13	56.1	62.7bd		16	18	64.1fh	> 0.99
	SM2	9	25				5	25

Accuracy¹ was calculated with the exception of 21 inconclusive cases of EUS; P² indicates a significant difference in Accuracy¹.

^bP < 0.0001;

^dP = 0.02;

^fP = 0.02;

^hP = 0.01. EUS: Endoscopic ultrasonography; CE: conventional endoscopy; Diff: Differentiated-type; Undiff: Undifferentiated-type; ER: Endoscopic resection.

Table 4 Diagnostic concordance between endoscopic ultrasonography and conventional endoscopy

		Indication for endoscopic resection
Diagnosis		Absolute criteria	Expanded criteria	Non-indication
Differentiated-type cancer (n = 99)
EUS	CE	(n = 42) (%)	(n = 25) (%)	(n = 32) (%)
Correct	Correct	39 (92.9)	19 (76)	20 (62.5)
Incorrect	Incorrect	0 (0)	3 (12)	11 (34.4)
Correct	Incorrect	1 (4.8)	1 (4)	1 (3.1)
Incorrect	Correct	1 (2.4)	2 (8)	0 (0)
Undifferentiated-type cancer (n = 33)
EUS	CE		(n = 8) (%)	(n = 25) (%)
Correct	Correct	-	8 (100)	15 (60)
Incorrect	Incorrect	-	0 (0)	1 (4)
Correct	Incorrect	-	0 (0)	5 (20)
Incorrect	Correct	-	0 (0)	4 (16)

EUS: Endoscopic ultrasonography; CE: Conventional endoscopy.

Table 5 Subgroup analysis of 13 differentiated-type cancers without UL and with SM2 diagnosed by conventional endoscopy¹

EUS	CE	n (%)
Correct	Correct	10 (76.9)
Correct	Incorrect	3 (23.1)
Incorrect	Correct	0 (0)
Incorrect	Incorrect	0 (0)

SM2 indicates invasion ≥ 500 μm into the submucosal layer. ¹The lesions with an ulcer scar or 0-I macroscopic type were excluded from this analysis because the diagnostic capability for those lesions was extremely low. EUS: Endoscopic ultrasonography; CE: Conventional endoscopy.

Table 6 Subgroup analysis of 13 undifferentiated-type cancers diagnosed as meeting the expanded criteria for endoscopic treatment by conventional endoscopy¹

EUS	CE	n (%)
Correct	Correct	10 (76.9)
Correct	Incorrect	3 (23.1)
Incorrect	Correct	0 (0)
Incorrect	Incorrect	0 (0)

¹One 0-I macroscopic type lesion was excluded from this analysis because the diagnostic capability of this type of lesions was extremely low. EUS: Endoscopic ultrasonography; CE: Conventional endoscopy.