TABLE 1.
Patient and center characteristics
| Total | Low volume (<12 cases/year) | Medium volume (12–48 cases/year) | High‐volume (>48 cases/year) | p | |
|---|---|---|---|---|---|
| No. of centers | 122 | 96 | 20 | 6 | |
| No. of patients | 11 346 | 2384 | 3344 | 5618 | |
| Annual case volume | 3.8 [0.8, 11.0] | 2.2 [0.5, 5.6] | 21.4 [14.6, 30.8] | 95.5 [55.6, 160.1] | <0.001 |
| Age | 64.2 (8.5) | 64.6 (8.6) | 64.3 (8.8) | 63.9 (8.3) | 0.001 |
| 19–60 | 3230 (28.5%) | 643 (27.0%) | 966 (28.9%) | 1621 (28.9%) | <0.001 |
| 61–70 | 4870 (42.9%) | 1021 (42.8%) | 1381 (41.3%) | 2468 (43.9%) | |
| 71–80 | 3009 (26.5%) | 653 (27.4%) | 907 (27.1%) | 1449 (25.8%) | |
| ≥81 | 237 (2.1%) | 67 (2.8%) | 90 (2.7%) | 80 (1.4%) | |
| Male | 10 502 (92.6%) | 2209 (92.7%) | 3068 (91.8%) | 5225 (93.0%) | 0.088 |
| Comorbidities | |||||
| Hypertension | 4680 (41.3%) | 991 (41.6%) | 1341 (40.1%) | 2348 (41.8%) | 0.272 |
| Diabetes mellitus | 2965 (26.1%) | 642 (26.9%) | 830 (24.8%) | 1493 (26.6%) | 0.114 |
| Coronary artery disease | 1603 (14.1%) | 295 (12.4%) | 426 (12.7%) | 882 (15.7%) | <0.001 |
| Chronic obstructive pulmonary disease | 991 (8.7%) | 170 (7.1%) | 323 (9.7%) | 498 (8.9%) | 0.003 |
| Chronic liver disease | 4022 (35.5%) | 921 (38.6%) | 1184 (35.4%) | 1917 (34.1%) | 0.001 |
| Chronic kidney disease | 149 (1.3%) | 37 (1.6%) | 44 (1.3%) | 68 (1.2%) | 0.471 |
| Cerebrovascular disease | 980 (8.6%) | 218 (9.1%) | 300 (9.0%) | 462 (8.2%) | 0.291 |
| Adjuvant therapy | <0.001 | ||||
| No neoadjuvant therapy | 3476 (30.6%) | 1115 (46.8%) | 1408 (42.1%) | 953 (17.0%) | |
| Neoadjuvant chemotherapy | 6325 (55.8%) | 1069 (44.8%) | 1751 (52.4%) | 3505 (62.4%) | |
| Neoadjuvant chemoradiotherapy | 1545 (13.6%) | 200 (8.4%) | 185 (5.5%) | 1160 (20.7%) | |
| Surgery year | |||||
| 2004–2010 | 5075 (44.7%) | 1090 (45.7%) | 1514 (45.3%) | 2471 (44.0%) | 0.270 |
| 2011–2017 | 6271 (55.3%) | 1294 (54.3%) | 1830 (54.7%) | 3147 (56.0%) |
Values are expressed as mean (standard deviation), median [interquartile range] or n (%).