Table 1 Characteristics of patients in the original cohort and post-matching cohort

N

262

183

115

115

Age, year

0.333

0.596

 < 60

142(54.2%)

90(49.9%)

65 (56.5%)

60 (52.2%)

 >=60

120(45.8%)

93(50.1%)

50 (43.5%)

55 (47.8%)

Gender

0.982

0.665

 Female

93(35.5%)

66(36.1%)

32 (27.8%)

36 (31.3%)

 Male

169 (64.5%)

117 (63.9%)

83 (72.2%)

79 (68.7%)

BMI

22.40 (3.31)

22.66 (3.62)

0.568

22.98 (3.91)

22.40 (3.95)

0.128

Preoperative intestinal obstruction

0.222

0.410

 No

218(83.2%)

143(78.1%)

89 (77.4%)

95 (82.6%)

 Yes

44 (16.8%)

40 (21.9%)

26 (22.6%)

20 (17.4%)

Preoperative Chemotherapy

0.019

1.000

 No

200(76.3%)

157(85.8%)

95 (82.6%)

94 (81.7%)

 Yes

62 (23.7%)

26 (14.2%)

20 (17.4%)

21 (18.3%)

Postoperative Chemotherapy

0.127

0.890

 No

89(44.0%)

76(41.5%)

39 (33.9%)

41 (35.7%)

 Yes

173(66.0%)

107(58.5%)

76 (66.1%)

74 (64.3%)

Surgical approach

< 0.001

 Laparoscopy

200(76.3%)

99(54.1%)

71 (61.7%

69 (60.0%)

0.893

 Open

62 (23.7%)

84 (45.9%)

44 (38.3%)

46 (40.0%)

Resection of liver metastases

0.054

1.000

 No

198(75.6%)

153(83.6%)

93 (80.9%)

92 (80.0%)

 Yes

64 (24.4%)

30 (16.4%)

22 (19.1%)

23 (20.0%)

Number of hepatic metastases

0.283

0.736

 1

 73 (27.9%)

40 (21.9%)

29 (25.2%)

30 (26.1%)

 2

155(59.2%)

113(61.7%)

69 (60.0%)

72 (62.6%)

 ≥ 3

34 (13.0%)

30 (16.4%)

17 (14.8%)

13 (11.3%)

ASA

0.295

0.617

 1

7 ( 2.7%)

7 ( 3.8%)

5 (4.3%)

6 (5.2%)

 2

204(77.9%)

137(74.9%)

94 (81.7%)

88 (76.5%)

 ≥ 3

51 (19.5%)

39 (21.3%)

16 (13.9%)

21 (18.3%)

Tumor location

0.088

0.944

 Left colon

74 (28.2%)

36 (19.7%)

29 (25.2%)

27 (23.5%)

 Right colon

86 (32.8%)

61 (33.3%)

42 (36.5%)

42 (36.5%)

 Rectum

102(38.9%)

86 (47.0%)

44 (38.3%)

46 (40.0%)

Tumor size, cm

0.068

0.943

 < 2

23 ( 8.8%)

6 ( 3.3%)

4 (3.5%)

5 (4.3%)

 2—5

194(74.0%)

145 (79.2%)

95 (82.6%)

94 (81.7%)

 > 5

45 (17.2%)

32 (17.5%)

16 (13.9%)

16 (13.9%)

Differentiation

< 0.001

0.543

 Well

19 ( 7.3%)

8 ( 4.4%)

7 (6.1%)

6 (5.2%)

 Moderately

208(79.4%)

114(62.3%)

85 (73.9%)

79 (68.7%)

 Poorly

35 (13.4%)

61 (33.3%)

23 (73.9%)

30 (26.1%)

T stage

0.154

0.332

 T1/T2

16 (6.1%)

5 (2.7%)

7 (6.1%)

3 (2.6%)

 T3/T4

246(93.9%)

178(97.3%)

108(93.9%)

112(97.4%)

N stage

< 0.001

0.865

 N0

117(44.7%)

21 (11.5%)

19 (16.5%)

21 (18.3%)

 N1

97 (37.0)

76 (41.5%)

61 (53.0%)

57 (49.6%)

 N2

48 (18.3%)

86 (47.0%)

35 (30.4%)

37 (32.2%)

No of sampled LNs

17.2(7.78)

17.0 (7.85)

0.785

17.6 (7.96)

17.3 (7.96)

0.865

No of positive LNs

1.68 (2.28)

4.63 (5.37)

< 0.001

1.73 (2.34)

4.66 (5.18)

0.848

Peri/intraneural invasion

< 0.001

0.790

 PNI(-)

188(71.8%)

80 (43.7%)

67 (58.3%)

64 (55.7%)

 PNI(+)

74 (28.2%)

103(56.3%)

48 (41.7%)

51 (44.3%)

Tumor deposits

< 0.001

0.891

 Absent

201(76.7%)

92(50.3%)

73 (63.5%)

75 (65.2%)

 Present

61 (23.3%)

91 (49.7%)

42 (36.5%)

40 (34.8%)

CEA level

0.003

0.546

 Normal

98 (37.4%)

43 (23.5%)

32 (27.8%)

27 (23.5%)

 Elevated

164(62.4%)

140(76.5%)

83 (72.2%)

88 (76.5%)

CA12−5 level

0.003

1.000

 Normal

226(86.3%)

137(74.9%)

93 (80.9%)

93 (80.9%)

 Elevated

36 (13.7%)

46 (25.1%)

22 (19.1%)

22 (19.1%)

CA19−9 level

0.132

0.787

 Normal

181(69.1%)

113(61.7%)

72 (62.6%)

69 (60.0%)

 Elevated

81 (30.9%)

70 (38.3%)

43 (37.4%)

46 (40.0%)