Long-term outcomes of endoscopic submucosal dissection for undifferentiated type early gastric cancer over 2 cm with R0 resection

Table 1 Baseline characteristics of single and R0 resected undifferentiated type early gastric cancer, n (%)

	Single UD (n = 137)	R0 resected UD (n = 79)	P value
Age, yr, mean (SD)	54.75 ± 14.20	51.47 ± 12.31	0.088
Male sex	70 (51.1)	42 (53.2)	0.779
Location of tumor			0.563
Upper	9 (6.6)	4 (5.1)
Middle	71 (51.8)	47 (59.5)
Lower	57 (41.6)	28 (35.4)
Gross endoscopic appearance			0.382
Elevated	31 (22.6)	12 (15.2)
Flat	35 (25.6)	20 (25.3)
Depressed	71 (51.8)	47 (59.5)
Tumor size, cm, mean (SD)	2.04 ± 1.19	1.71 ± 1.06	0.266
≤ 2 cm	73 (53.3)	51 (64.6)
2.1-3 cm	42 (30.7)	19 (24.0)
> 3 cm	22 (16.0)	9 (11.4)
Depth of invasion			0.043
M1	0 (0)	0 (0)
M2	56 (40.9)	40 (50.6)
M3	66 (48.2)	39 (49.4)
SM1	4 (2.9)	0 (0)
SM2	7 (5.1)	0 (0)
SM3	4 (2.9)	0 (0)
Histology			> 0.999
Poorly differentiated adenocarcinoma	89 (65.0)	51 (64.6)
Signet ring cell carcinoma	48 (35.0)	28 (35.4)
Enbolc resection	127 (92.7)	79 (100)	0.060
Curative resection	60 (43.8)	51 (64.6)	0.005
Non curative resection	77 (56.2)	28 (35.4)
Over 2 cm	64 (46.7)	28 (35.4)	0.118
Submucosal invasion	15 (10.9)	0 (0)	0.004
Positive lateral margin	29 (21.1)	0 (0)	< 0.001
Positive vertical margin	9 (6.6)	0 (0)	0.028
Lymphovascular invasion	5 (3.7)	0 (0)	0.274
R0 resection	95 (69.3)	79 (100)	< 0.001
Follow-up periods, months, mean (SD)	68.83 ± 52.10	79.71 ± 45.42	0.123

M1 epithelium, M2 lamina propria, M3 muscularis mucosa, SM1 upper 1/3 and less than 500 μm of submucosa, SM2 middle 1/3 of submucosa, SM3 lower 1/3 of submucosa.

Table 2 Comparison between less than 2 cm and over 2 cm, n (%)

	Group A	Group B	P value
	Less than 2 cm (n = 51)	Over 2 cm (n = 28)
Age, yr, mean (SD)	49.84 ± 11.90	54.43 ± 12.71	0.114
Male sex	28 (54.9)	14 (50)	0.814
Location of tumor			0.567
Upper	3 (5.9)	1 (3.6)
Middle	28 (54.9)	19 (67.8)
Lower	20 (39.2)	8 (28.6)
Gross endoscopic appearance			0.148
Elevated	10 (19.6)	2 (7.1)
Flat	10 (19.6)	10 (35.7)
Depressed	31 (60.8)	16 (57.2)
Tumor size, cm, mean (SD)	1.06 ± 0.60	2.89 ± 0.58	< 0.001
≤ 2 cm	51 (100)	0 (0)
2.1-3 cm	0 (0)	19 (67.9)
> 3 cm	0 (0)	9 (32.1)
Depth of invasion			0.062
M1	0 (0)	0 (0)
M2	30 (58.8)	10 (35.7)
M3	21 (41.2)	18 (64.3)
Histology			0.630
Poorly differentiated adenocarcinoma	34 (66.7)	17 (60.7)
Signet ring cell carcinoma	17 (33.3)	11 (39.3)
Follow-up periods, months, mean (SD)	82.57 ± 43.62	74.51 ± 48.92	0.454

M1 epithelium, M2 lamina propria, M3 muscularis mucosa.

Table 3 Summary of clinical outcomes

	Group A	Group B	P value
	Less than 2 cm (n = 51)	Over 2 cm (n = 28)
Recurrence, n (%)	1 (2)	1 (3.6)	> 0.999
Local recurrence	1 (2)	1 (3.6)
Regional lymph node	0 (0)	0 (0)
Distant metastasis	0 (0)	0 (0)
Regional lymph node metastasis	0 (0)	0 (0)
Distant metastasis	0 (0)	0 (0)
Death	0 (0)	0 (0)
Recurrence free survival, months, mean (SD)	204.12 ± 3.77	178.82 ± 9.03	0.7501

¹Log-rank test (Mantel-Cox).