Appropriateness of the institute certification system for esophageal surgeries by the Japan Esophageal Society: evaluation of survival outcomes using data from the National Database of Hospital-Based Cancer Registries in Japan

Table 1 Comparison of patient characteristics

	AIBCES	Non-AIBCES	p
Number of institutes	53	141
Number of patients	1343	792
Age (mean, SD)	64.7 (8.2)	65.8 (8.2)	<0.01¹⁾
Number of males (%)	1146 (85%)	680 (85%)	0.74²⁾
T classification			0.55³⁾
Tis	8 (1%)	0 (0%)
T1	424 (32%)	212 (27%)
T2	240 (17%)	215 (27%)
T3	578 (43%)	289 (37%)
T4	56 (4%)	44 (6%)
Tx	37 (3%)	32 (3%)
N classification			0.34³⁾
N0	609 (45%)	386 (49%)
N1	675 (50%)	366 (46%)
N2	18 (1%)	16 (2%)
N3	3 (0%)	3 (0%)
Nx	38 (3%)	21 (3%)
N classification			0.32²⁾
N0	609 (45%)	386 (49%)
N1–3	696 (52%)	385 (49%)
Nx	38 (3%)	21 (3%)
M classification			0.12²⁾
M0	1190 (89%)	724 (91%)
M1	112 (8%)	51 (6%)
Unknown	41 (3%)	17 (2%)
Clinical stage (UICC)			0.26³⁾
cStage 0	9 (1%)	0 (0%)
cStage I	325 (24%)	182 (23%)
cStage II	436 (33%)	314 (40%)
cStage III	420 (31%)	216 (27%)
cStage IV	113 (8%)	54 (7%)
Unknown	40 (3%)	26 (3%)
Surgery			<0.01⁴⁾
Thoracotomy	1085 (81%)	677 (86%)
Thoracoscopic	254 (19%)	110 (14%)
Unknown	4 (0%)	5 (1%)
Adjuvant therapy			<0.01⁴⁾
No radiation or chemotherapy	642 (48%)	404 (51%)
+Radiation therapy	20 (2%)	21 (3%)
+Chemotherapy	552 (41%)	245 (31%)
+Radiation and chemotherapy	127 (10%)	122 (15%)
Unknown	2 (0%)	0 (0%)

AIBCES Authorized Institute for Board Certified Esophageal Surgeon
Statistical comparisons were made using ¹⁾ Student’s t test, ²⁾ the Chi squared test, ³⁾ Wilcoxon-type test for trend, ⁴⁾ Fisher’s exact test