Table 1 Baseline characteristics before and after 1:1 propensity-score matching of training case to non-training case colorectal cancer resections

Age (median, range) in years

70 (29–92)

72 (29–90)

71 (27–92)

0.677^a

Gender

0.191^b

 Male

320 (55.2%)

55 (57.9%)

46 (48.4%)

 Female

260 (44.5%)

40 (42.1%)

49 (51.6%)

BMI¹ (kg/m²)

26 (17–52)

26 (17–43)

26 (17–47)

0.959^a

ASA²

0.653^b

 1

58 (10.0%)

9 (9.5%)

13 (13.7%)

 2

379 (65.3%)

66 (69.5%)

62 (65.3%)

 3

141 (24.3%)

20 (21.1%)

20 (21.1%)

Tumour area

0.821^b

 Rectum

223 (38.4%)

28 (29.5%)

32 (33.7%)

 Left-sided colon

172 (29.7%)

28 (29.5%)

26 (27.4%)

 Right-sided colon

185 (31.9%)

39 (41.1%)

37 (38.9%)

Previous surgery

0.424^b

 No

391 (67.4%)

65 (68.4%)

70 (73.7%)

 Yes

189 (32.6%)

30 (31.6%)

25 (26.3%)

T stage

0.250^c

 T0

6 (1.0%)

2 (2.1%)

0 (0.0%)

 T1

58 (10.0%)

8 (8.4%)

9 (9.5%)

 T2

134 (23.1%)

18 (18.9%)

22 (23.2%)

 T3

323 (55.7%)

54 (56.8%)

59 (62.1%)

 T4a

51 (8.8%)

12 (12.6%)

5 (5.3%)

 T4b

8 (1.4%)

1 (1.1%)

0 (0.0%)

N stage

0.346^c

 N0

366 (63.1%)

57 (60.0%)

65 (68.4%)

 N1

140 (24.1%)

24 (25.3%)

22 (23.2%)

 N2

74 (12.8%)

14 (14.7%)

8 (8.4%)

AJCC³ tumour stage

0.523^c

 0

4 (7%)

1 (1.1%)

0 (0.0%)

 1

150 (25.9%)

20 (21.1%)

23 (24.2%)

 2

201 (34.7%)

35 (36.8%)

40 (42.1%)

 3

203 (35.0%)

36 (37.9%)

27 (28.4%)

 4

22 (3.8%)

3 (3.2%)

5 (5.3%)

Radiotherapy

0.771^c

 None

534 (92.1%)

88 (92.6%)

87 (91.6%)

 Short course

13 (2.2%)

2 (2.1%)

4 (4.2%)

 Long course

31 (5.3%)

4 (4.2%)

4 (4.2%)

 Postoperative

2 (0.3%)

1 (1.1%)

0 (0.0%)

Type of chemotherapy

0.180^c

 None

371 (64.0%)

56 (58.9%)

68 (71.6%)

 Neoadjuvant

37 (6.4%)

5 (5.3%)

3 (3.2%)

 Adjuvant

169 (29.1%)

34 (35.8%)

24 (25.3%)

 Palliative

3 (0.5%)

0

0

Procedure

0.585^c

 Anterior resection

314 (54.1%)

44 (46.3%)

45 (47.4%)

 Sigmoid colectomy

24 (4.1%)

6 (6.3%)

1 (1.1%)

 Left colectomy

14 (2.4%)

2 (2.1%)

3 (3.2%)

 Right colectomy

149 (25.7%)

34 (35.8%)

34 (35.8%)

 Extended right colectomy

35 (6.0%)

3 (3.2%)

3 (3.2%)

 Hartmann’s procedure

5 (0.9%)

1 (1.1%)

1 (1.1%)

 APR⁴

27 (4.7%)

3 (3.2%)

7 (7.4%)

 Total/subtotal colectomy

5 (0.95%)

1 (1.1%)

1 (1.1%)

 Panproctocolectomy

7 (1.2%)

1 (1.1%)

0 (0.0%)

Stoma

0.301^c

 No stoma

345 (59.5%)

64 (67.4%)

63 (66.3%)

 Temporary ileostomy

183 (31.6%)

23 (24.2%)

24 (25.3%)

 Permanent ileostomy

9 (1.6%)

2 (2.1%)

0 (0.0%)

 Temporary colostomy

7 (1.2%)

2 (2.1%)

0 (0.0%)

 Permanent colostomy

36 (6.2%)

4 (4.2%)

8 (8.4%)