Table 1 Patient baseline clinical characteristics

Gender

0.525

 Male

187 (63.2%)

261 (60.8%)

 Female

109 (36.8%)

168 (39.2%)

Age (years)

59.50 ± 10.65

60.36 ± 10.71

0.301

Body mass index (kg/m²)

24.24 ± 3.03

24.13 ± 3.35

0.655

Neoadjuvanst therapy

0.029

 Yes

89 (30.1%)

98 (22.8%)

 No

207 (69.9%)

331(77.2%)

ASA score

0.104

 I

30 (10.1%)

45 (10.5%)

 II

254 (85.8%)

350 (81.6%)

 III

12 (4.1%)

34 (7.9%)

Smoking

0.460

 Yes

103 (34.8%)

138 (32.2%)

 No

193 (65.2%)

291 (67.8%)

Alcohol consumption

0.610

 Yes

54 (18.2%)

72 (16.8%)

 No

242 (81.8%)

357 (83.2%)

Hypertension

0.351

 Yes

88 (29.7%)

114 (26.6%)

 No

208 (70.3%)

315 (73.4%)

Diabetes

0.116

 Yes

48 (16.2%)

52 (12.1%)

 No

248 (83.8%)

377 (87.9%)

Previous history of abdominal surgery

0.718

 Yes

44 (14.9%)

68 (15.9%)

 No

252 (85.1%)

361 (84.1%)

Preoperative intestinal obstruction

0.732

 Yes

32 (10.8%)

43 (10%)

 No

264 (89.2%)

386 (90%)

Preoperative hemoglobin levels (g/L)

118.33 ± 8.98

121.45 ± 11.92

0.349

Preoperative serum albumin levels (g/L)

44.15 ± 3.88

43.39 ± 5.28

0.151

Tumor location (from anal verge, cm)

9.26 ± 2.51

9.38 ± 2.52

0.800

Depth of tumor invasion (T) category

0.233

 T0

19 (6.4%)

13 (3%)

 T1

18 (6.1%)

27 (6.3%)

 T2

56 (19%)

80 (18.6%)

 T3

175 (59%)

258 (60.1%)

 T4

28 (9.5%)

51(11.9%)

Lymph node metastases (N) category

0.855

 N0

167 (56.6%)

240 (55.9%)

 N1

85 (28.8%)

120 (28%)

 N2

44 (14.6%)

69 (16.1%)

Metastasis

0.080

 M0

267 (90.2%)

402 (93.7%)

 M1

29 (9.8%)

27 (6.3%)

Pathological TNM stage

0.296

 I

57 (19.3%)

84 (19.6%)

 II

87 (29.4%)

137 (31.9%)

 III

104 (35.1%)

168 (39.2%)

 IV

29 (14.1%)

27 (6.4%)