Table 1 Baseline clinicopathological characteristics
Characteristics | Before PSM (n = 611) | After PSM (n = 254) | ||||||
|---|---|---|---|---|---|---|---|---|
Right-sided group (n = 141) | Left-sided group (n = 470) | P value | SMD | Right-sided group (n = 127) | Left-sided group (n = 127) | P value | SMD | |
Mean age (± SD), years | 57 (± 12) | 55 (± 11) | 0.313 | − 0.099 | 56 (± 12) | 54 (± 12) | 0.381 | 0.086 |
Gender, n (%) | Â | Â | 0.538 | 0.065 | Â | Â | 0.894 | 0.016 |
 Male | 92 (65.2) | 321 (68.3) |  |  | 84 (66.1) | 86 (67.7) |  |  |
 Female | 49 (34.8) | 149 (31.7) |  |  | 43 (33.9) | 41 (32.3) |  |  |
Primary tumor characteristics | ||||||||
 Chemotherapy prior to CRC resection |  |  | 0.218 |  |  |  | 0.364 |  |
  Yes | 37 (26.4) | 156 (33.3) |  |  | 35 (27.8) | 43 (33.9) |  |  |
  No | 103 (73.6) | 313 (66.7) |  |  | 91 (72.2) | 84 (66.1) |  |  |
 Surgery of CRC and CRLM, n (%) |  |  | 0.067 |  |  |  | 0.900 |  |
  Staged | 69 (48.9) | 271 (57.7) |  |  | 62 (48.8) | 64 (50.4) |  |  |
  Combined | 72 (51.1) | 199 (42.3) |  |  | 65 (51.2) | 63 (49.6) |  |  |
 Tumor size, mean (± SD), cm | 4.2 (± 2.3) | 3.6 (± 2.2) | 0.011* |  | 4.2 (± 2.3) | 3.7 (± 2.4) | 0.048* |  |
 T stage, n (%) |  |  | 0.524 |  |  |  | 0.841 |  |
  T1/T2 | 9 (6.4) | 40 (8.5) |  |  | 8 (6.3) | 10 (7.9) |  |  |
  T3/T4 | 118 (83.7) | 393 (83.6) |  |  | 114 (89.8) | 112 (88.9) |  |  |
  unknown | 14 (9.9) | 37 (7.9) |  |  | 5 (3.9) | 5 (3.9) |  |  |
 N stage, n (%) |  |  | 0.546 | − 0.061 |  |  | 0.363 | -0.058 |
  N0 | 52 (39.7) | 188 (40.0) |  |  | 51 (40.2) | 43 (33.9) |  |  |
  N1/N2 | 79 (60.3) | 249 (53.0) |  |  | 76 (59.8) | 84 (66.1) |  |  |
  Unknown | 0 (0) | 33 (7.0) |  |  |  |  |  |  |
 TNM stage, n (%) |  |  | 0.441 |  |  |  | 0.348 |  |
  I | 2 (1.4) | 10 (2.1) |  |  | 2 (1.6) | 0 (0.0) |  |  |
  II | 7 (5.0) | 43 (9.1) |  |  | 7 (5.5) | 9 (7.1) |  |  |
  III | 21 (14.9) | 73 (15.5) |  |  | 21 (16.5) | 20 (15.7) |  |  |
  IV | 106 (75.2) | 331 (70.4) |  |  | 96 (75.6) | 98 (77.2) |  |  |
  Unknown | 5 (3.5) | 13 (2.8) |  |  | 1 (0.7) | 0 (0.0) |  |  |
 Postoperative chemotherapy, n (%) |  |  | 0.256 |  |  |  | 0.475 |  |
Yes | 103 (73.0) | 366 (77.9) | Â | Â | 91 (71.7) | 97 (76.4) | Â | Â |
No | 38 (27.0) | 104 (22.1) | Â | Â | 36 (28.3) | 30 (23.6) | Â | Â |
CRLM characteristics | ||||||||
 Presentation of CRLM, n (%) |  |  | 0.253 | − 0.113 |  |  | 0.883 | − 0.062 |
  Metachronous | 35 (24.8) | 140 (29.8) |  |  | 31 (24.4) | 29 (22.8) |  |  |
  Synchronous | 106 (75.2) | 330 (70.2) |  |  | 96 (75.6) | 98 (77.2) |  |  |
 Preoperative chemotherapy, n (%) |  |  | 0.008* | 0.268 |  |  | 0.900 | − 0.045 |
  Yes | 68 (48.2) | 287 (61.1) |  |  | 64 (50.4) | 62 (48.8) |  |  |
  No | 73 (51.8) | 183 (38.9) |  |  | 63 (49.6) | 65 (51.2) |  |  |
 Preoperative CEA (μg/L), (> 200/≤ 200) [n (%)] | 6/135 (4.3/95.7) | 23/447 (4.9/95.1) | 0.755 | − 0.008 | 6/121 (4.7/95.3) | 5/122 (3.9/96.1) | 1.000 | − 0.042 |
 Preoperative CA19-9 (kU/L), , (> 35/≤ 35) [n (%)] | 30/110 (21.4/78.6) | 97/370 (20.8/79.2) | 0.867 |  | 26/100 (20.6/79.4) | 24/103 (18.9/81.1) | 0.754 |  |
 Tumor size (cm), median (IQR) | 3.0 (2.0–4.5) | 2.8 (1.6–4.0) | 0.095 | − 0.164 | 3.0 (1.8–4.0) | 3.0 (1.5–4.0) | 0.944 | − 0.013 |
 Position, n (%) |  |  | 1.000 |  |  |  | 0.196 |  |
  Unilobar | 79 (56.4) | 263 (56.6) |  |  | 72 (57.1) | 81 (65.3) |  |  |
  Bilobar | 61 (43.6) | 202 (43.4) |  |  | 54 (42.9) | 43 (34.7) |  |  |
 Number of tumors, n (%) |  |  | 0.627 | 0.082 |  |  | 0.528 | − 0.015 |
  Multiple | 79 (56.0) | 275 (58.5) |  |  | 73 (57.5) | 67 (52.8) |  |  |
  Single | 62 (44.0) | 195 (41.5) |  |  | 54 (42.5) | 60 (47.2) |  |  |
 R0 resection, n (%) |  |  | 1.000 |  |  |  | 0.886 |  |
  Yes | 119 (84.4) | 396 (84.4) |  |  | 106 (83.5) | 106 (84.1) |  |  |
  No | 22 (15.6) | 73 (15.6) |  |  | 21 (16.5) | 20 (15.9) |  |  |
 Postoperative chemotherapy, n (%) |  |  | 0.455 |  |  |  | 1.000 |  |
  Yes | 98 (69.5) | 342 (72.8) |  |  | 89 (70.1) | 90 (70.9) |  |  |
  No | 43 (30.5) | 128 (27.2) |  |  | 38 (29.9) | 37 (29.1) |  |  |
 CRS score, n (%) |  |  | 0.538 |  |  |  | 0.922 |  |
  1–2 | 90 (64.7) | 312 (67.7) |  |  | 88 (71.0) | 88 (70.4) |  |  |
  3–5 | 49 (35.3) | 149 (32.3) |  |  | 36 (29.0) | 37 (29.6) |  |  |