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 (%) | 0.538 | 0.065 | 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) | 91 (71.7) | 97 (76.4) | ||||
| No | 38 (27.0) | 104 (22.1) | 36 (28.3) | 30 (23.6) | ||||
| 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) | ||||
PSM propensity score matching, SD standard deviation, IQR inter-quartile range, T stage tumor stage, N stage node stage, CRLM colorectal liver metastases, CEA carcinoembryonic antigen, CA 19-9 carbohydrate antigen 19-9, R0 resection hepatectomy on patients with clear histological margins, SMD standardized mean differences
*P < 0.05